It is not a message likely to get through.

In the closing weeks of Mr. Trump’s campaign, his efforts to demonize immigrants, whether they are from Venezuela, Haiti or elsewhere, have gotten ever more lurid — and more impervious to the facts, even those provided by Republican allies such as Mr. Coffman. Last month, the former president began portraying Aurora, a sprawling suburb of Denver, population 404,219, as “a war zone” overrun by a violent Venezuelan street gang, Tren de Aragua.

Despite the entreaties of Aurora city officials in both parties to stay away, Mr. Trump is taking his case to Aurora itself on Friday. He will head there for an afternoon rally at the Gaylord Rockies Resort & Convention Center, a location that is decidedly not overrun by Venezuelan gangs.

He is not welcome, declared Crystal Murillo, a Democratic city councilwoman and a Mexican American.

“My message is, Trump doesn’t belong here,” she said in an interview. “His divisiveness, his rhetoric, is not what Aurora is about.”

The tall tales of Colorado’s third largest city being occupied by armed Venezuelans stem from the novel excuse given by an out-of-state landlord, CBZ Management, to the city of Aurora for the utterly deplorable conditions in which residents of three of its apartment complexes were living.

In July, CBZ told the city that its property managers were unable to make the repairs that tenants and city officials were demanding because armed leaders of Tren de Aragua had taken over the complexes, violently expelled the managers and begun extracting rent payments from the migrant residents themselves.

A public relations firm hired by the landlord enlisted Denver’s Fox affiliate to run a story on the supposed takeover. Mr. Coffman, the mayor, and a conservative city councilwoman, Danielle Jurinsky, repeated the landlord’s story, though they have since retracted their statements. And a video of armed men in one of the complexes began circulating in conservative media.

By the time Mr. Trump picked up the cause, the fever dream of a huge Colorado city overrun by migrant criminals — a city that is home to the University of Colorado’s medical school and one of the most prominent children’s hospitals in the country — had taken hold.

“The reality is that the concerns about Venezuelan gang activity have been grossly exaggerated,” Mr. Coffman said Friday morning, trying once again to set the record straight. “The incidents were limited to several apartment complexes in this city of more than 400,000 residents.”

The city put out its own statement on Friday, also pre-emptively fact-checking the former president ahead of his rally. “A gang has not ‘taken over’ the city,” it said. “The overstated claims fueled by social media and through select news organizations are simply not true. It is tragic that select individuals and entities have mischaracterized our city based on some specific incidents.”

(The city did not name any of the “select individuals” it had in mind.)

Major crimes, it continued, “are down more than 17 percent in Aurora.” And “the city is actively deploying every legal tool to ensure CBZ Management is accountable for its properties and meets its responsibilities.”

The Aurora Police Department has secured all three apartment complexes. Ten men associated with Tren de Aragua have been identified, and nine have been arrested, said Ryan Luby, a city spokesman. Six armed men seen in a viral video taken by a doorbell camera in one of the apartment complexes have now been identified and one has been arrested, he added.

One of the CBZ-owned complexes has also been seized and closed down, and two others are now in receivership, Ms. Murillo said. The city is encouraging the bank that seized the properties to sell them to a reputable, low-income housing company to make sure that the poor residents — some but not all of whom are Venezuelan migrants — remain housed.

Lawyers for CBZ and for Zev Baumgarten, the man officials identified as the landlord and who has been criminally charged for neglect, have said repeatedly that the city, not the company, is to blame for the deplorable conditions in the apartments.

“It’s the government’s responsibility to protect property and — more importantly — to protect the people who live there,” said Matthew C. Arentsen, a lawyer for CBZ. “The government failed in this responsibility.”

That assertion has been denied strongly by city officials, including the Republican mayor and Democratic City Council members, all of whom say CBZ is an out-of-state slumlord that has exploited clients, bilked the city and created a fiasco now weighing on the city’s reputation.

The tales of rampaging gangs have been “a distraction from the real issues,” Ms. Murillo said, “a lack of accountability for corporate landlords and a lack of housing.”

Representative Jason Crow, a Democrat who lives in Aurora, said Friday he will keep calling Mr. Trump out on his “lies” about the city, regardless of how impervious the former president is to fact-checking. The Aurora visit is another sign that Mr. Trump “knows that he is losing,” Mr. Crow said.

“We set the standard for welcoming people from around the world, and we do it remarkably well,” the congressman said of his city. “We are not going to allow ourselves to be victimized by his politics.”

The event, announced by Fox News on Friday, will focus on “issues impacting women ahead of the election,” the network said, including abortion, day care, child care, health care and the economy.

It will not be shown live. The event will be taped on Tuesday evening, in Cumming, Ga., and air on Wednesday at 11 a.m. The moderator is the Fox host Harris Faulkner.

Mr. Trump’s Democratic opponent, Ms. Harris, is set to appear for her own town hall on CNN on Oct. 23, with voters in Pennsylvania. That event will be aired live.

CNN has said Mr. Trump has an open invitation to appear on the network for a town hall.

Fox News on Friday said the same regarding Ms. Harris. “Fox News has a standing invitation to Vice President Harris for a town hall event of equal stature which has been extended to her campaign multiple times since she became a candidate for president in August,” the network said in a statement.

Mr. Trump, whose performance at the ABC debate in September was widely viewed as lackluster, has repeatedly signaled that he has no intention of meeting Ms. Harris again on the debate stage before Election Day.

Chris LaCivita, one of Mr. Trump’s campaign managers, formally declined Fox News’s invitation for a debate in Pennsylvania on Oct. 23 or 27 several hours after the network first proposed it, according to a person familiar with the exchange. Ms. Harris’s campaign has not commented on the Fox invitation to debate, with the anchors Bret Baier and Martha MacCallum moderating.

If Ms. Harris accepted the Fox News invitation, it could allow her to sharpen her argument that Mr. Trump is afraid to joust with her face to face — even on a channel where he enjoys sympathetic coverage from commentators.

Agreeing to a Fox debate, though, could increase pressure on Ms. Harris to appear on Fox for her own solo town hall, which her campaign has so far been reluctant to do.

In an interview set to air next week, Ms. Harris’s husband, Doug Emhoff, told the MSNBC host Joe Scarborough that he believed Mr. Trump was afraid to debate the vice president.

“You saw the first debate, didn’t you? Yeah, that’s why,” Mr. Emhoff said when Mr. Scarborough asked what was stopping Mr. Trump, according to an advance excerpt. “He’s afraid that that’s going to happen again.”

“I know we’ve got some pressing issues to talk about,” Charlamagne said on the program on Friday.

The event will last an hour and air Tuesday evening across some 140 radio stations nationwide, according to the Harris campaign.

Ms. Harris’s planned appearance comes as her campaign works to solidify its support with Black men. Ms. Harris would be the second Black president and first Black woman in the office, but Democrats view the vice president’s relatively soft support from Black men as a significant concern in the election.

On Thursday, former President Barack Obama delivered a stern message to Black men, who he said were “coming up with all kinds of reasons and excuses” not to back Ms. Harris.

“Part of it makes me think that, well, you just aren’t feeling the idea of having a woman as president,” Mr. Obama said as he visited a group of campaign volunteers and officials at a field office in Pittsburgh ahead of a campaign appearance. The choice between Ms. Harris and former President Donald J. Trump “isn’t a close call,” Mr. Obama said.

“The Breakfast Club,” which has a reach that extends far beyond radio in its podcast form and in viral videos on YouTube, has long been a venue for candidates to appeal to Black voters. It has also been a site of some memorable moments in presidential politics.

Appearing on the show in 2016, Hillary Clinton said she carried hot sauce around in her bag. (Charlamagne immediately replied, “People are going to see this and say, ‘OK, she’s pandering to Black people.’”) In 2020, Joseph R. Biden Jr. said on the program, “If you have a problem figuring out whether you’re for me or Trump, then you ain’t Black.” Mr. Biden received criticism for the comment and apologized, and Charlamagne, whose real name is Lenard Larry McKelvey, endorsed Mr. Biden anyway.

In 2019, Ms. Harris, then a senator from California seeking the Democratic presidential nomination, appeared on “The Breakfast Club” and discussed her support for marijuana legalization and her taste in music, which led to a backlash over her responses.

When asked about the previous election during an hourlong interview with Lulu Garcia-Navarro, a host of “The Interview,” a Times podcast published each Saturday, the Republican vice-presidential nominee responded that he was “focused on the future.” It was the same phrase he used to evade the same question during his debate with his Democratic rival, Gov. Tim Walz of Minnesota.

“There’s an obsession here with focusing on 2020,” Mr. Vance said in the interview. “I’m much more worried about what happened after 2020, which is a wide-open border, groceries that are unaffordable.”

When pressed a second time, Mr. Vance pivoted to a complicated counterargument: He suggested Mr. Trump would have won more votes in 2020 had social media companies not limited posts about a New York Post story about the contents of a laptop that belonged to Hunter Biden, President Biden’s son. Trump allies had maintained that documents on the laptop linked President Biden to corrupt business dealings, but those claims were unfounded.

“Senator Vance, I’m going to ask you again,” Ms. Garcia-Navarro said. “Did Donald Trump lose the 2020 election?”

“Did big technology companies censor a story that independent studies have suggested would have cost Trump millions of votes?” Mr. Vance replied.

“Senator Vance,” Ms. Garcia-Navarro continued. “I’m going to ask you again, did Donald Trump lose the 2020 election?”

“And I’ve answered your question with another question,” Mr. Vance said. “You answer my question and I’ll answer yours.”

On her fifth request for a yes-or-no answer, Ms. Garcia-Navarro pointed out that there was “no proof, legal or otherwise,” of election fraud.

Mr. Vance dismissed that as “a slogan.”

“I’m not worried about this slogan that people throw, ‘Well, every court case went this way,’” Mr. Vance said. “I’m talking about something very discrete — a problem of censorship in this country that I do think affected things in 2020.”

During his 90-minute debate with Mr. Walz, Mr. Vance twice refused to answer a direct question about whether Mr. Trump had lost the 2020 election. It was widely considered his weakest debate moment and may have turned off voters. In CNN’s focus group of seven undecided Michigan voters who watched the debate, the only person who settled on a pick after the event said he would support Vice President Kamala Harris specifically because of Mr. Vance’s refusal to acknowledge the 2020 election results.

Mr. Vance’s interview with The Times covered a range of subjects, including his conversion to Catholicism and the backlash over his attacks on “childless cat ladies.” But the exchange on the 2020 results showed he still had not found an answer to put the last election behind him. Acknowledging the truth that Mr. Biden won, of course, would discredit Mr. Trump’s claims and risk angering the former president.

Mr. Trump has anchored his party to this issue — and raised concerns about the reaction that could follow the results on Nov. 5 — by continuing to dispute the 2020 contest.

Mr. Trump seemed to acknowledge in a podcast interview last month that he had indeed “lost by a whisker,” but then insisted during his debate with Ms. Harris on Sept. 10 that “that was said sarcastically.”

“Look, there’s so much proof,” Mr. Trump said during the debate, after refusing to acknowledge his defeat. “All you have to do is look at it. And they should have sent it back to the legislatures for approval. I got almost 75 million votes.”

Mr. Trump received 74.2 million votes, but the presidency is decided by the Electoral College, not a nationwide popular vote. Still, Mr. Biden received 81.3 million votes.

Three weeks later, at the vice-presidential debate, Mr. Vance was asked directly by Mr. Walz whether Mr. Trump lost.

“Tim, I’m focused on the future,” Mr. Vance told him. “Did Kamala Harris censor Americans from speaking their mind in the wake of the 2020 Covid situation?”

“That is a damning non-answer,” Mr. Walz shot back.

In his Times interview, Mr. Vance said he would not have voted to certify the 2020 results, and added that “we commit to a peaceful transfer of power” in 2024.

“If there are problems, of course, in the same way that Democrats protested in 2004 and Donald Trump raised issues in 2020,” Mr. Vance said, “we’re going to make sure that this election counts.”

In her answer, Ms. Harris strove to connect, gently urging Ms. Castillo to “remember your mother as she lived.” But the vice president’s response also underscored how much her hard-line immigration message has focused on enforcement rather than reform, as former President Donald J. Trump uses the border to paint Ms. Harris as a weak and ineffective leader.

While Ms. Harris called the nation’s immigration system “broken” and pointed out that the first bill proposed by the Biden-Harris administration would have created an earned pathway to citizenship for many undocumented immigrants, she quickly turned to the topic of the southern border — and condemned Mr. Trump for helping kill a bill that would have devoted more resources to securing it.

“Real leadership is about solving the problems on behalf of the people,” she said at the town hall, which was held in Las Vegas and will be broadcast at 10 p.m. Eastern time. Many questions were asked in Spanish and translated for her. Hispanic voters could help decide the election, but Ms. Harris’s support among them is lagging.

On Thursday, she also faced intense and emotional questions on health care and the economy, giving her a chance to display a greater degree of empathy and humanity than in the more choreographed interviews she has recently given. Much of the conversation centered on themes that Democratic presidential candidates have used to appeal to Latino voters for decades, including promises to stimulate small businesses, lower costs for families and create more legal pathways for undocumented workers.

But Ms. Harris also took sharp jabs at Mr. Trump, whom she described as a “sore loser” who had directed a “violent mob” against Congress. She denounced his profession to be “a dictator on Day 1” and called for the preservation of democracy and abortion rights, underscoring the stakes of the election and her party’s recognition that Latino voters are not a monolithic bloc with a narrow set of interests.

“This is an extraordinary time,” she said, her voice rising. “This is not a debate about trickle-down economic theory. It’s literally about, Do we support a democracy and the Constitution of the United States?”

Mr. Trump is set to appear in his own Univision town hall on Oct. 16.

Hispanic voters could play a crucial role in November, particularly in the two Southwestern battleground states: Nevada, where roughly 1 in 5 voters are Hispanic; and Arizona, where roughly 1 in 4 are. President Biden won both states in 2020.

But polls show Ms. Harris with less support from Hispanic voters than Mr. Biden carried four years ago. In Arizona, Ms. Harris is polling at 49 percent among Hispanic voters, compared with 41 percent for Mr. Trump, according to a New York Times/Siena College poll last month. Roughly 60 percent of Hispanic voters in Arizona backed Mr. Biden in 2020.

Mr. Trump is leading Ms. Harris in Arizona overall, while Ms. Harris maintains a narrow edge in Nevada, Times polling averages show. Ms. Harris could lose both states and still carve a path to the White House if she were to hold onto the “blue wall” of Michigan, Pennsylvania and Wisconsin, where the race is vanishingly close.

Her campaign has nevertheless continued to aggressively court Latino voters in Arizona and Nevada, pouring money into TV, digital and radio ads in English and Spanish, and deploying staff members and volunteers to knock on doors. On Thursday evening, Ms. Harris held a get-out-the-vote rally outside Phoenix.

There, she criticized Mr. Trump for threatening to undo the Affordable Care Act, and got raucous applause when she mentioned how the late Senator John McCain, a longtime Arizona Republican, had cast a decisive vote in 2017 thwarting efforts by Mr. Trump and Republicans to repeal it.

At the edges of the rally, Carmen Garza, 49, who works in insurance, leaned against a wall to wipe the sweat off her face as she reflected on how her own family reflected the broader divides among Arizona’s Latinos.

Her parents were Mexican American farmworkers and were dedicated Democrats, but she said her brother was leery of Ms. Harris. Ms. Garza has tried to talk up Ms. Harris’s proposals to expand tax breaks for first-time startup businesses or have Medicare cover in-home care for older people. But he has been unmoved.

“He was like, ‘I did better when Trump was in office,’” she said.

Ms. Harris is struggling in particular among Hispanic men, polls show. On Wednesday, the Harris-Walz camp introduced “Hombres con Harris,” or “Men with Harris,” a series of events focused on health care and the economy and aimed at swaying Hispanic men. Last month in Las Vegas, Julie Chavez Rodriguez, Ms. Harris’s campaign manager, and campaign surrogates attended a popular boxing match between Canelo Álvarez and Edgar Berlanga.

As in her other appeals — in advertisements and at events — Ms. Harris underscored her personal story as the daughter of immigrants who worked her way up to some of the highest offices in the United States at the Univision town hall.

And she did seek to balance her tougher message on immigration with promises to expand and improve legal pathways for undocumented immigrants and Dreamers, or people brought into the country illegally as children.

“So our Dreamers — this is again a very big example of what the price it is to pay for our broken immigration system,” she said, describing the group of immigrants as friends, classmates, business leaders and military officers.

Still, she once again remained silent on her past promise to use the power of the presidency to unilaterally give them a way to citizenship.

Mike Noble, a pollster who works in Arizona and Nevada, said that Ms. Harris’s decision to appear at the Univision town hall was significant. He described Hispanic voters as the largest swing group in the region: “It is the most movable and the most sizable — the opportunity and the threat for the two major parties.”

In Arizona, the top two issues for Latino voters have been the economy and immigration. In Nevada, home to a more socially liberal and transient population of hotel and casino service workers, the top issues have tended to be the economy, abortion rights and tips, according to Mr. Noble’s polling firm. Both Ms. Harris and Mr. Trump have proposed to exempt tips from federal taxes.

“Latinos are going to have an outsized influence in this election,” said Representative Robert Garcia of California, who attended the town hall and is an ally of Ms. Harris. “The margins are so tight.”

There was one question that seemed to stump Ms. Harris on Thursday and cast her as less than nimble on her feet.

After an audience member asked her to name “three virtues” possessed by Mr. Trump, she instead attacked him for using “belittling language” before mustering up one positive quality, his love for his family.

She then seemed to run out of steam, saying she had met Mr. Trump just once — on the debate stage last month — and “didn’t really know him, to be honest.”

“So I don’t really have that much more to offer you,” she concluded.

Citing “reports I’m getting from campaigns and communities,” he called out what he said was flagging enthusiasm for Ms. Harris compared with the support he received when he was running for the presidency in 2008.

“You’re coming up with all kinds of reasons and excuses,” Mr. Obama said. “I’ve got a problem with that.

“Part of it makes me think that, well, you just aren’t feeling the idea of having a woman as president, and you’re coming up with other alternatives and other reasons for that,” Mr. Obama continued, adding that the “women in our lives have been getting our backs this entire time.

“When we get in trouble and the system isn’t working for us, they’re the ones out there marching and protesting.”

The stern words from the former president were meant to address worrying signs for Ms. Harris, including that her support among Black voters is still lower than what President Biden received when he won the state in 2020, according to a poll last month from The New York Times, The Philadelphia Inquirer and Siena College. Ms. Harris’s advisers and a raft of Democratic strategists believe that if anyone can lift Black voter turnout, it is Mr. Obama.

“He’s got, obviously, tremendous appeal to Black voters,” the Democratic strategist James Carville said. “He has tremendous appeal to suburban whites, which is another big part of the coalition. And he drives Trump nuts.”

Early voting has already begun in Pennsylvania, which Ms. Harris must almost certainly win to defeat Mr. Trump. She holds a narrow lead in the polls there, having overcome the significant deficit she inherited from Mr. Biden. Democrats are hoping for high voter turnout in the state’s biggest cities, Pittsburgh and Philadelphia.

Mr. Obama remains adored by Democrats, making him a natural surrogate for Ms. Harris on the campaign trail. More than 90 percent of Democrats and many independents view him favorably, according to an August survey by The Economist and YouGov — well above other Democrats, including Mr. Biden, Bill Clinton and Hillary Clinton.

Ms. Harris was an early supporter of Mr. Obama, flying to Iowa in 2007 to knock on doors for the junior senator from Illinois when she was the district attorney of San Francisco.

The Pittsburgh rally kicked off Mr. Obama’s plans to return the favor. The former president plans to barnstorm battleground states in the final weeks of the election to emphasize the importance of voting.

On Thursday night before over 4,500 people at the University of Pittsburgh’s Fitzgerald Field House, Mr. Obama largely made the case for Ms. Harris by delivering a searing takedown of Mr. Trump. He mocked Mr. Trump as unable to relate to everyday Americans — quipping, to jeers, that he has most likely never changed a diaper or a tire. The attacks turned serious, too, as Mr. Obama upbraided Mr. Trump’s response to the deadly hurricanes that have devastated Southeastern states.

Mr. Obama pointed to a Trump rally after Hurricane Helene devastated the Carolinas and Georgia, where Mr. Trump made a series of false claims. He contrasted it with visits Ms. Harris and Mr. Biden made to the states in the days after, where they met with emergency workers and comforted families.

“Donald Trump, at a rally, just started making up stories about the Biden administration withholding aid from Republican areas and siphoning off aid to give to undocumented immigrants,” he said. “Just made the stuff up.”

“Everybody knew it wasn’t true,” he said. “Even local Republicans said it was not true.”

Mr. Obama said Mr. Trump’s allegations carried grave consequences because the claims could discourage people from seeking help.

“The idea of intentionally trying to deceive people in their most desperate and vulnerable moments,” he said, “and my question is: When did that become OK?”

Mr. Obama acknowledged the frustration that people are feeling after a pandemic that gutted the economy — which has been a vulnerability for Ms. Harris’s campaign.

“I get why people are looking to shake things up,” he said. “What I cannot understand is why anybody would think that Donald Trump will shake things up in a way that is good for you, Pennsylvania.”

“There is absolutely no evidence that this man thinks about anybody but himself,” he added.

Mr. Obama also used Mr. Trump’s record to broaden his call to all men to support Ms. Harris.

“And by the way, I’m sorry, gentlemen, I’ve noticed this, especially with some men who seem to think Trump’s behavior of bullying and putting people down is a sign of strength,” he said. “And I am here to tell you that is not what real strength is. It never has been.”

“Real strength is about working hard and carrying a heavy load without complaining,” he continued, his voice rising into a shout. “Real strength is about taking responsibility for your actions and telling the truth even when it’s inconvenient. Real strength is about helping people who need it and standing up for those who can’t always stand up for themselves. That is what we should want for our daughters and for our sons, and that is what I want to see in a president of the United States of America.”

Nicholas Nehamas contributed reporting from Las Vegas.

Mr. Trump claimed his plan would “stimulate massive domestic auto production and make car ownership dramatically more affordable” for families.

But before he got to his new proposal, Mr. Trump often rambled, reviving his false claims about the 2020 election, mocking President Biden’s 2020 campaign crowds, praising Elon Musk’s rockets. At one point, as he criticized Vice President Kamala Harris, Mr. Trump did something that politicians rarely do: He took a pointed dig at the city that was hosting him.

“Our whole country will end up being like Detroit if she’s your president,” he said. “You’re going to have a mess on your hands.”

Gov. Gretchen Whitmer of Michigan, a Democrat, blasted Mr. Trump’s comments in a social media post, saying that “you better believe Detroiters won’t forget this in November.”

As Mr. Trump spoke about his proposals to revive the auto industry, he used some of the same kind of violent, cataclysmic language he often uses to vilify immigrants.

“After our victory in 2016, the Michigan auto industry was on its knees, begging for help, gasping,” he said at one point. Later, he claimed that international corporations had been allowed to “come in and raid and rape” the nation, a word choice he underscored. “That’s right, I used the word,” he said. “They raped our country.”

Mr. Trump’s proposals were the latest example of his dangling new, and expensive, tax benefits to groups of voters that he sees as key to his election chances next month. The former president has already called for eliminating taxes on tips, overtime and Social Security benefits. On Wednesday night, he released a statement calling for a tax cut for Americans who live abroad, who must still file a tax return with the Internal Revenue Service.

It is not clear how much it would cost the federal government in lost tax revenue if car loan interest were fully deductible.

Mr. Trump’s proposal to make interest on car loans tax deductible could be likened to the mortgage interest deduction, which Mr. Trump limited in the 2017 tax cuts that he enacted as president. Mr. Trump expanded the standard deduction, which has pushed far fewer Americans to itemize deductions on their tax returns. In 2017, before the law went into effect, 31 percent of Americans itemized their deductions on their tax returns, according to the Tax Policy Center. In 2020, just 10 percent of Americans itemized, the center found.

Higher-income Americans are much more likely to still itemize deductions on their tax bills — and therefore would be the main beneficiaries of Mr. Trump’s idea. (The mortgage interest deduction encourages people to buy homes, which tend to gain value over time; the merits of a federal tax policy that encourages people to borrow to buy automobiles, which lose value quickly, could be more questionable.)

During his speech Mr. Trump also promised to keep “Chinese-produced autonomous vehicles” off American streets, an effort already being undertaken by the Biden administration, which last month proposed banning Chinese-developed software from internet-connected vehicles in the United States. Though few Chinese vehicles are on U.S. roads, federal officials called the move a proactive effort to address potential national security issues.

Mr. Trump also reiterated many of his manufacturing proposals, including his call for tariffs and his plan to offer companies tax breaks and other benefits if they move their manufacturing to the United States or keep it there.

The former president also signaled that he was prepared to take more aggressive protectionist measures to shield the automobile sector from foreign competition in a second term, saying he would take steps to prevent China and other countries from passing products through other countries to avoid U.S. tariffs.

And Mr. Trump said he would formally notify Mexico and Canada that he planned to renegotiate the trade deal that he reached with them in 2018. He warned them again that he would seek to impose 100 percent tariffs on Chinese cars that are manufactured in Mexico and imported to the United States.

It had been expected that parts of the trade deal would be revisited in 2026. Ms. Harris said two weeks ago that she would open the review process. She was one of 10 senators to vote against the agreement.

Mr. Trump’s remarks, held at the Sound Board Theater inside the MotorCity Casino and Hotel, were given to an audience atypical for a Trump event. Unlike a raucous rally, the business leaders in the room were more muted in their response.

And the Economic Club’s president, Steve Grigorian, noted that a number of Democratic officials were in attendance, including Michigan’s secretary of state, Jocelyn Benson, who in 2020 faced armed protesters at her house chanting that they refused to accept that Mr. Trump had lost that election.

Mr. Trump acknowledged her attendance while complaining about Democrats’ stance on voter identification laws.

Before Mr. Trump’s speech, the Harris campaign held a call with Shawn Fain, the president of the United Automobile Workers, which endorsed Ms. Harris. Mr. Fain — who Mr. Trump attacked repeatedly during Thursday’s speech — criticized the former president’s economic record, saying his time in office was marked by “plant closings, job loss and union busting.”

Voters in the Detroit metropolitan area will be crucial if Mr. Trump hopes to win Michigan, a battleground state that helped deliver his victory in 2016 but that he lost in 2020. His speech on Thursday was his fourth event in the state in the last two weeks.

Polls have shown Mr. Trump and Ms. Harris locked in a tight contest in the state. According to a recent survey from The New York Times and Siena College, Mr. Trump’s perceived strength on economic issues has cut into an advantage that Ms. Harris held in early August, shortly after she replaced Mr. Biden on the Democratic ticket.

After speaking for nearly two hours, Mr. Trump sat down with John Rakolta, one of his former ambassadors to the United Arab Emirates, to take questions. As some people left the room, Mr. Rakolta acknowledged the lengthy remarks.

“That was a tremendous amount of information that you’ve given to us,” he said.

Andrew Duehren and Ana Swanson contributed reporting.