Mr. Trump’s inner circle was not in possession of the full details before the story was published on CNN’s website, but they knew the bar for what would qualify as a “bad” story for Mr. Robinson was high. The candidate had already quoted a statement attributed to Adolf Hitler and mocked the teen survivors of the Parkland school shooting, and Mr. Trump’s advisers had recently started seeking distance from Mr. Robinson.

The Trump team had heard the CNN story had something to do with pornographic websites and the phrase “Black Nazi,” according to two people with direct knowledge of the internal discussions, who spoke on the condition of anonymity.

It didn’t help that at the same time they were waiting on the self-identifying Nazi story to come out, Mr. Trump was attending events in Washington, D.C., designed to promote his support for the state of Israel and the Jewish people. It also didn’t help that just months ago the former president had praised Mr. Robinson, who is Black, as “Martin Luther King on steroids.”

After CNN published its report, Mr. Trump’s first reaction was that he wanted nothing to do with the scandal and didn’t see why he should get involved, according to two people with knowledge of the situation. His impulse was to ignore the controversy and power through. People close to the former president are holding out hope that Mr. Robinson will still decide to quit the race, despite his early defiant statement of his intention to continue his run for governor.

But with Mr. Trump preparing to visit North Carolina for a rally on Saturday, he’s expected to talk about the controversy in passing, either on his Truth Social platform or once he’s in the state. People close to him anticipate that he will deliver a version of a comment he has made about countless supporters or former aides: that he hardly knows the guy.

The CNN article that was finally published Thursday — which said Mr. Robinson had defended slavery, posted about enjoying watching transgender pornography, recounted how he had gone “peeping” on women in public gym showers as a teenager and called himself a “black NAZI” on a pornographic site’s message board — has scrambled Republican plans for winning North Carolina.

How state Republican leaders and Trump campaign officials expect to repair the damage remained unclear on Friday. One statewide North Carolina Republican sought to separate Mr. Trump from Mr. Robinson hours after the story had broken.

“It was a tough day, but we must stay focused on the races we can win,” Senator Thom Tillis wrote on X, adding, with a reference to the North Carolina General Assembly: “We have to make sure President Trump wins NC and support the outstanding GOP candidates running for key NCGA and judicial races. If Harris takes NC, she takes the White House. We can’t let that happen.”

Earlier on Thursday before the CNN story had broken, the chairman of the Republican National Committee, Michael Whatley, a fellow North Carolinian, sounded out Mr. Robinson about rumors of the impending story. Mr. Robinson insisted that anything that was coming was false — a denial he would repeat publicly later in the day.

As they waited for the story to drop, Mr. Trump’s allies and advisers discussed privately whether it would be possible to pressure Mr. Robinson to quit the race. They quickly concluded that direct pressure probably would not work and could in fact backfire, leading him to dig in and defend himself. Mr. Robinson did so anyway. Plus, the state election board might not allow him to be removed from the ballot whether he stayed in the race or not.

In a phone interview shortly before the story ran, a person close to the Trump campaign described the situation in North Carolina, with dry understatement, as “less than ideal.” Establishment Republicans in North Carolina widely viewed Mr. Robinson as an outright electoral danger — to them and to Mr. Trump. His views were extreme even for the Trumpified G.O.P. His hard-line position on abortion gave the Democrats plenty to work with in a state that Mr. Trump won in 2020 and that would be an essential step in his path to winning in 2024.

In public and private polls in North Carolina, Vice President Kamala Harris had already pulled nearly even with Mr. Trump. Mr. Robinson lagged far behind his Democratic rival, the state’s attorney general, Josh Stein, and the constant swirl of controversies around him already dominated the news coverage of the state.

The Harris campaign quickly spliced together some of the praise Mr. Trump had heaped on Mr. Robinson. “You have to cherish him,” Mr. Trump once said. “He’s like a fine wine.”

Asked about the CNN story on Thursday, a Trump spokeswoman, Karoline Leavitt, released a statement that made no mention of any part of it. It did not include the words “Mark Robinson.”

Instead, Ms. Leavitt said Mr. Trump would win the White House and called North Carolina a “vital part of that plan.”

“We will not take our eye off the ball,” she said.

Even if it was too late to get Mr. Robinson’s name off the ballots, the bulk of Mr. Trump’s advisers would be happy for him to drop out of the race and concede the governor’s mansion seven weeks before Election Day. In the meantime, they planned to monitor their internal polls to see if the controversy was having any effect on Mr. Trump.

But while they’re concerned about Mr. Robinson, there are limits to how much damage the Trump team believes any down-ballot candidate can do to the former president, even one with this level of self-inflicted damage. Mr. Trump is a unique political figure. It’s hard to find an American who doesn’t have a fixed opinion about him — and certainly of his character. He’s no stranger to weathering allegations of personal scandal.

Jared Kushner used to say to colleagues that his father-in-law was “a tie-dyed shirt — you spill wine on it, and it doesn’t matter.” A few extra stains — whether by his own doing or by others — almost never dramatically alter the public’s perception of Mr. Trump, since his earliest days as a candidate.

In 2022, Mr. Trump supported a string of candidates in midterm races who were controversial. Chief among them was Herschel Walker, a former football player who ran for a Senate seat in Georgia and was the subject of a series of accusations about his personal life during the campaign, including assertions that he had paid for a girlfriend’s abortion.

None of the allegations ended up damaging Mr. Trump, who was Mr. Walker’s most enthusiastic backer. But at the time, Mr. Trump was not a candidate himself.

Now, however, Mr. Trump is set to share a ballot with Mr. Robinson. And Democrats are eager to remind voters of that fact.

The former president has been reluctant to publicly turn against Mr. Robinson, who has said many nice things about him. Mr. Trump likes Mr. Robinson and has been impressed by his charisma, praising him as having the oratorical skills of a modern-day Martin Luther King Jr.

Mr. Robinson first caught the attention of people in Mr. Trump’s orbit a couple of years ago, when he delivered a screed against transgender people. His speech at a church opened with the line, “Ain’t but two genders.” The clip went viral online.

But after seeing recent polls in recent months — and the drag on the ticket that Mr. Robinson represented — Mr. Trump began distancing himself from the lieutenant governor, following the advice of his advisers.

On Thursday, the attorney general’s office took the rare step of weighing in on the proposed rules, saying they “very likely exceed the board’s statutory authority.”

The fight comes as the election board is under increasing pressure from critics already concerned that it has been rewriting the rules of the game in a key swing state to favor former President Donald J. Trump, including potentially disrupting certification of the election if Mr. Trump loses in November. Last month, the board granted local officials new power over the election-certification process, a change that opponents say could sow chaos.

Elizabeth Young, a senior assistant attorney general, characterized five specific new election proposals as either exceeding the board’s legal reach or as an unnecessary redundancy, including the hand-counting proposal.

“There are thus no provisions in the statutes cited in support of these proposed rules that permit counting the number of ballots by hand at the precinct level prior to delivery to the election superintendent for tabulation,” Ms. Young wrote in a letter, which was reviewed by The New York Times. “Accordingly, these proposed rules are not tethered to any statute — and are, therefore, likely the precise type of impermissible legislation that agencies cannot do.”

The legal advisory follows a letter from the secretary of state and a memorandum from the Georgia Association of Voter Registration and Election Officials, a nonpartisan collective of local election officials, both warning the election board that it was overstepping its authority.

The mounting legal advice from both the top law enforcement official in the state and the leading election officials sets up a choice for the election board on Friday: Heed the mass of guidance or ignore it all to pass another package of election rules that include right-wing policy goals.

At a news conference on Friday morning, Janelle King, a Republican appointee to the election board, pushed back against criticism that the board was making fundamental changes to the process so close to Election Day.

“I am absolutely considering time,” said Ms. King, “but I also consider the job that we have been tasked to do, and sometimes it doesn’t always agree.”

She continued, “We are raising the standard because the right to elect our leaders is a fundamental core principle of a republic.”

The Georgia State Election Board, once a bureaucratic backwater in the state election apparatus, has thrust itself into national headlines with a 3-2 right-wing majority that has aligned itself closely with rules rooted in election conspiracy theories.

Last month, the board passed a rule upending decades of settled Georgia law, allowing local election officials to conduct a “reasonable inquiry” investigation before certifying election results, a rule Democrats and election experts said could disrupt the certification process.

The board also approved an investigation into the 2020 election in Fulton County, long a desire of right-wing election conspiracy theorists but far from the list of priorities of local election officials or the secretary of state.

The event brought together members of over 100 online groups that have coalesced around Ms. Harris since she became the Democratic nominee, including White Dudes for Harris, Cat Ladies for Kamala and Latinas for Harris. Also joining virtually were celebrities that included Chris Rock, Ben Stiller, Jennifer Lopez, Tracee Ellis Ross and Meryl Streep.

But the most remarkable moments in the roughly 90-minute forum came when Ms. Winfrey did what she does best: orchestrating an interview that connects with everyday Americans whose experiences illustrate the strife of a country craving empathy. The discussions were heavy at times, with members of the audience — in person and at home — in tears.

Ms. Harris has not often spoken off the cuff or at length about many issues since she catapulted to the top of the ticket after President Biden dropped out of the race. Here she addressed questions from the audience and Ms. Winfrey about issues like immigration and gun violence, and what would happen if her opponent, former President Donald J. Trump, didn’t accept the results of the election should he lose a second time.

Ms. Harris spoke more elaborately than she has before on the effects of illegal immigration — a key issue for voters and a vulnerability in her campaign. She cited the devastating effects of fentanyl, overwhelmed border patrol agents and strained resources for prosecuting transnational criminal organizations. She pointed out that a bill that Mr. Trump had helped kill in Congress would have helped confront these problems, and she vowed to resurrect that bill and sign it.

On abortion rights, one of her strongest issues after a Supreme Court with three Trump-appointed justices overturned Roe v. Wade, she yielded to those who have been affected.

The mother and sister of Amber Thurman spoke publicly for the first time about her death by sepsis after waiting 20 hours, an outcome of the state’s abortion ban, for a hospital to treat her complications from an abortion pill. Ms. Thurman’s story, reported by ProPublica, has crystallized the consequences of restrictions on reproductive health.

“Amber was not a statistic,” her mother said as members of the crowd teared up. “She was loved by a family, a strong family, and we would have done whatever to get my baby, our baby, the help that she needed.”

Ms. Harris, who met with the family before the event, used the moment to highlight Mr. Trump’s abortion record. She will travel to Georgia on Friday to deliver remarks on reproductive rights. “It’s a health care crisis,” she said on Thursday. “It’s a health care crisis that affects the patient and the profession.”

Also in the crowd at the forum, held outside Detroit, was Natalie Griffith, a 15-year-old student who was shot twice in algebra class by a classmate during a campus attack on Sept. 4 at Apalachee High School, also in Georgia. Her mother, Marilda Griffith, sobbed telling the story of how that day unfolded.

“The whole world needs to hear that we women, that have our children — we have a job,” Ms. Griffith said. “That job is to protect our children. That job is to protect our nation.”

Ms. Harris agreed, citing the “bone-chilling” sight of a sea of students raising their hands when, on tours across the country, she asks if they have participated in active-shooter drills.

Meryl Streep asked Ms. Harris how she was preparing for the “long slog of shenanigans” that may come should Mr. Trump not accept the election’s results and incite violence reminiscent of the Capitol riot on Jan. 6, 2021.

Ms. Harris said her team was ready for Mr. Trump to challenge the election: The “lawyers are working.” But she encouraged people to talk with their friends about misinformation, to protect poll workers and to not be afraid to vote.

Several hundred people attended the event at Studio Center. Other notable attendees included the state’s governor, Gretchen Whitmer, and Jotaka Eaddy, a collaborator with Ms. Winfrey on the event and founder of Win With Black Women, the first group to draw tens of thousands of people to a Zoom fund-raiser for Ms. Harris’s campaign.

Ms. Winfrey’s skill of drawing out the humanity and vulnerability of her subjects was on display, including with the often guarded vice president.

At the beginning of the interview, Ms. Winfrey said she had noticed a change in Ms. Harris since she entered the race, as if a “veil dropped.” She asked if Ms. Harris had felt that, too. “I felt a sense of responsibility, to be honest with you, and with that comes a sense of purpose,” Ms. Harris said.

Midway through the conversation, as Ms. Harris discussed her support for the Second Amendment, she acknowledged that she may have gotten too comfortable when Ms. Winfrey said she hadn’t known that Harris was a gun owner until the debate. “If somebody breaks in my house, they’re getting shot,” Ms. Harris said, then caught herself. “I probably should not have said that,” she said, laughing. “But my staff will deal with that later.”

An hour before the event, Mr. Trump’s campaign sent a statement accusing Ms. Harris of campaigning “with an out-of-touch celebrity, further confirming that the Democrat party is not the party of hardworking Americans — it is the party of elitists.”

Ms. Winfrey, a registered independent who had never spoken at a party convention before, gave a full-throated endorsement of Ms. Harris last month at the Democratic National Convention.

Ms. Winfrey’s endorsement is a coveted one, as she has largely shied away from politics, reserving her influence for a few major races. In 2007, she endorsed Barack Obama, then a senator from Illinois, and hit the campaign trail for him in Iowa.

In announcing the virtual rally, Ms. Winfrey said she wanted to use it to motivate people to vote.

During the event, which was also aimed at mobilizing volunteers to make phone calls and to knock on doors in their communities, Ms. Harris’s campaign chairwoman stressed that it was still a “razor-thin race.”

Added Ms. Winfrey to the audience: “We love having you here, but the rah-rah moment is going to end, and then we need to get to work.”

Mr. Trump on Thursday offered an extended airing of grievances against Jewish Americans who have not voted for him. He repeated his denunciation of Jews who vote for Democrats before suggesting that the Democratic Party had a “hold, or curse,” on Jewish Americans and that he should be getting “100 percent” of Jewish votes because of his policies on Israel.

Jews, who make up just over 2 percent of America’s population, are considered to be one of the most consistently liberal demographics in the country, a trend that Mr. Trump has lamented repeatedly this year as he tries to chip away at their longstanding affiliation with Democrats.

Much as he repeatedly spins a doomsday vision of America as he campaigns this year, Mr. Trump has pointed to Hamas’s deadly Oct. 7 massacre and to the war in Gaza as he has insisted that Israel will “cease to exist” within a few years if he does not win in November.

“With all I have done for Israel, I received only 24 percent of the Jewish vote,” he said during his earlier speech on Thursday, at a campaign event where he spoke to an audience of prominent Republican Jews — including Miriam Adelson, the megadonor who is a major Trump benefactor — and lawmakers. Mr. Trump added that “I really haven’t been treated very well, but it’s the story of my life.”

During his speeches, Mr. Trump made no mention of Mark Robinson, the lieutenant governor of North Carolina. Mr. Robinson, the Republican nominee for governor, came under fire as CNN reported that on a pornographic forum, he had once called himself a “black NAZI” and defended slavery. Mr. Trump once endorsed him and called him “Martin Luther King on steroids.”

But during his speech, while lamenting the decline of the pro-Israel lobby over the last 15 years, Mr. Trump noted that in the past, “if you said something about a Jewish person or something about Israel that was bad, you were out of politics.”

Mr. Trump has been repeatedly criticized for remarks that have either attacked Jewish Democrats or drawn on antisemitic tropes. During his presidency, he accused American Jews who did not back him of being disloyal, a remark criticized for evoking a longstanding trope suggesting that Jews have a “dual loyalty” and are often more loyal to Israel than to their own nations. Mr. Trump returned to that on Thursday as he wondered aloud why he was not getting more support from American Jews for his foreign policy involving Israel.

Mr. Trump also drew withering criticism in 2022 for dining with Nick Fuentes, an outspoken antisemite and influential white supremacist, shortly after starting his 2024 campaign. Earlier this month, Mr. Trump traveled with Laura Loomer, a far-right activist known for sexist, homophobic, transphobic, anti-Muslim and occasionally antisemitic remarks.

Earlier this year, the former president also repeatedly played down the violence at a white supremacist rally in Charlottesville, Va., that occurred during his term as president in 2017. In Charlottesville’s aftermath, Mr. Trump drew a moral equivalency between the white supremacists — who brandished swastikas, Confederate flags and “Trump-Pence” signs — and peaceful counterprotesters, asserting that there were “very fine people on both sides.”

In his earlier speech on Thursday, Mr. Trump also rattled off a list of antisemitic incidents and hate crimes against Jews — particularly on college campuses — that he sought to tie to Vice President Kamala Harris, his Democratic rival, asserting that Ms. Harris “hates Israel.”

In contrast, Mr. Trump portrayed himself to Jews as “your defender, your protector,” and “the best friend Jewish Americans have ever had in the White House.”

“I’m the one that’s protecting you,” Mr. Trump said near the end of his speech, adding, in a reference to Democrats, that “these are the people that are going to destroy you.”

Later, speaking at the Israeli American Council’s summit, Mr. Trump invoked the Holocaust, comparing the current geopolitical moment to the period that preceded the systematic murder of six million Jews. Then, he continued by saying that if Ms. Harris won in November, “you will have the most anti-Israel president by far.”

Morgan Finkelstein, a spokeswoman for the Harris campaign, rejected Mr. Trump’s accusations, saying that Ms. Harris “stands steadfastly against antisemitism both at home and abroad and will do the same as president.”

Over the past two weeks, a new super PAC called Duty to America has spent almost $7 million on anti-Harris messaging like this, putting content aimed at millennials and Gen-Z voters in digital ads and text message programs. The group was formed in June and has not yet disclosed any contributors, but the size of the expenditures in September suggests some backing from major donors.

The group, created by a Republican campaign-finance compliance official, did not return requests for comment. Its website describes the super PAC as an “organization dedicated to electing leaders who understand and are focused on solving the challenges facing the far too many Americans who feel left behind by politicians and that their American Dream is out of reach.”

Cost-of-living arguments are nothing new in politics, but the specific issues the super PAC is targeting are novel.

“Democrats are dialed in on one thing: banning our nicotine pouches,” the narrator of an ad airing on YouTube says. “If Democrats spent their time fixing real problems, instead of telling us what to do, we wouldn’t be in this mess. Kamala Harris, stay away from our pouches.”

Ms. Harris has not publicly said anything about nicotine pouches, though other Democrats have. Earlier this year, Chuck Schumer, the Senate majority leader, asked the F.D.A. to investigate one popular brand of the pouches, Zyn, and their effect on teenagers.

Nicotine pouches have become a sensation among social-media influencers and younger Americans, particularly those on the right, including Tucker Carlson, a former Fox News host turned podcaster. (Mr. Carlson promoted Zyn pouches but has now turned against the brand over supposed political differences.)

Several other digital videos and ads seem targeted to young men who are followers of sports and gambling, using plenty of betting metaphors.

“Fifty bucks — that used to be a pretty good wager,” another ad says. “Enough to make winning sweet, but not enough to hurt if you lost. But now, 50 bucks is too much to lose and not enough to win. What can you even do with 50 bucks today?”

The ad continues: “This November, vote no on Harris and the Democrats. They’re a losing bet every time.”

Other spots stress that Ms. Harris is “taking your vote for granted.”

There has been concern among Democrats about losing ground with young, male voters. The ads appear to be an effort by pro-Trump forces to make inroads with that very constituency.

The lawsuit argues that state law prohibits election officials from notifying voters of such errors and allowing them to be fixed in time to have their ballot counted, a process known as curing.

More than half of states allow curing for some types of errors, such as a missing signature or date on a ballot envelope, or a signature that doesn’t match the one election officials have on file for the voter. Former President Donald J. Trump railed against the process as he falsely alleged election fraud in 2020 and tried to overturn his loss, and it has been a point of contention since then in Pennsylvania and in other states.

Democrats are more likely than Republicans to vote by mail, and Republicans have sought to restrict mail voting in various ways, casting their efforts as fighting fraud. There is no evidence of significant election fraud in mail ballots or any other form of voting.

The new lawsuit notes that different counties in Pennsylvania have adopted different procedures for curing, and it argues that this violates a requirement in the state constitution that election processes be “uniform.” It also argues that the state legislature would need to authorize any curing process and that existing state law precludes curing because it forbids the “inspection” and “opening” of mail-in ballots before Election Day.

“The Election Code thus bars election officials from providing notice of defects in time for them to be cured,” it says.

It also takes issue with two actions by state officials: first, guidance to voters that they can cast a provisional ballot on Election Day if they believe their mail ballot was defective, and second, the generation of automated emails to voters whose mail ballots are marked as potentially defective, informing them that they have the right to cast a provisional ballot.

Provisional ballots are a standard option for voters who are unable to vote normally at their polling place because of questions about their eligibility — for example, voters whose names don’t appear on the rolls, but who believe they are registered. The voter’s eligibility is assessed after the fact, and the provisional ballot is counted if they are deemed to have been eligible.

The Pennsylvania secretary of state’s office said it was reviewing the lawsuit.

“The Shapiro administration supports allowing voters to rectify technical deficiencies so their vote is counted,” a spokesman, Matt Heckel, said. “We will continue to fight for every eligible citizen’s right to vote and have their voice heard.”

With less than seven weeks until the election, all five Republicans who represent the state in Congress are pushing for Nebraska to return to a winner-take-all system of awarding electoral votes that had been used before 1992 and was based on the statewide popular vote.

Under the state’s current hybrid system, its electoral votes are split: Two go to the winner of the statewide popular vote, and the other three are based on who wins the popular vote in each of Nebraska’s three U.S. House districts. Maine also has a hybrid system.

In 2016, Mr. Trump secured all five of Nebraska’s electoral votes, but he was denied a sweep in 2020 when President Biden won the popular vote in the Second District, which includes Omaha, the state’s most populous city. The area, which has become known in Nebraska as the “blue dot,” is near where Gov. Tim Walz of Minnesota, Ms. Harris’s running mate, was born.

Bracing for a close election, Mr. Trump’s allies are trying again to blot out the “blue dot” — which, in a close race, could play an outsize role — after their previous efforts stalled.

If Mr. Trump flips Arizona, Georgia and Nevada, states won by Mr. Biden in 2020, there is still a pathway for Ms. Harris to win the presidency by holding onto the other states that Mr. Biden won, including Pennsylvania, Wisconsin and Michigan.

Under that scenario, Ms. Harris and Mr. Trump would each end up with 269 electoral votes, one short of the 270 needed to win the presidency. A victory in Nebraska’s Second District for Ms. Harris could break that tie. Otherwise, the House of Representatives would break the tie, with each state delegation getting one vote, giving Republicans the advantage.

In a letter sent on Wednesday to the governor and the State Legislature’s speaker, who are both Republicans, the group called for an end to the hybrid system.

“It is past time that Nebraska join 48 other states in embracing winner-take-all in presidential elections,” the group wrote in the letter.

Also on Wednesday, Senator Lindsey Graham, Republican of South Carolina, visited Nebraska, where he too advocated for the state to change its rules.

Representatives for Mr. Graham, who The Nebraska Examiner reported had visited the governor’s mansion, did not respond to requests for comment. When he was asked by reporters on Capitol Hill on Thursday about his trip to Nebraska, he said that the Trump campaign had not dispatched him to make the case for the winner-take-all system.

“Trump’s going to win the state by 20 points,” Mr. Graham said, according to CBS News.

The Trump campaign did not respond to requests for comment. The Harris-Walz campaign did not immediately provide a comment.

Changing the state’s system of awarding electoral votes would require a special session of the Legislature, a unicameral body that is officially nonpartisan but is controlled by Republicans.

Carol Blood, a Democratic state senator who is running for Congress in the First District, criticized the push, saying on Thursday that its timing was suspect and that a winner-take-all system would make Nebraska less relevant on the national political map.

“The blue dot is what keeps Nebraska from being a flyover state,” said Ms. Blood, who lost an open-seat race for governor in 2022 to Jim Pillen, a Republican.

Representatives for Mr. Pillen did not immediately respond to requests for comment on Thursday.

In a statement last week, the governor declared his support for awarding all five of Nebraska’s electoral votes to the winner of the statewide popular vote.

“As I have also made clear, I am willing to convene the Legislature for a special session to fix this 30-year-old problem before the 2024 election,” Mr. Pillen said. “However, I must receive clear and public indication that 33 senators are willing to vote in such a session to restore winner-take-all.”

Mike McDonnell, a Republican state senator who was a Democrat until earlier this year, has emerged as a potential swing vote in the process, according to reports in Nebraska. When he changed parties in April, he said that he opposed a winner-take-all system.

Barry Rubin, a spokesman for Mr. McDonnell, told The Nebraska Examiner on Thursday, “Senator McDonnell has heard compelling arguments from both sides,” adding, “And, as of today, (he) is still a no.”

Mr. McDonnell did not respond to a request for comment from The New York Times.