Vice President Kamala Harris made an aggressive move to cut into Donald Trump’s polling lead on immigration, traveling to the southern border for the first time as the Democratic nominee on Friday to lay out her plans to tackle what she described as a problem that has languished for decades.

Harris, during her trip to the key swing state of Arizona, lambasted Trump for his role earlier this year in tanking a border security bill that was the product of months of bipartisan negotiations.

It was one of Harris’ more specific policy speeches since becoming the Democratic nominee, attempting to use her past as California’s attorney general to prove that she has what it takes to attack Trump on his signature issue.

“It was the strongest border security bill we have seen in decades. It was endorsed by the Border Patrol union. And it should be in effect today, producing results in real time, right now, for our country,” she said at a rally in Douglas, a town on the US-Mexico border.

“But Donald Trump tanked it. He picked up the phone and called some friends in Congress and said, ‘Stop the bill,’” she said. “He prefers to run on a problem instead of fixing a problem. And the American people deserve a president who cares more about border security than playing political games and their personal political future.”

The former president responded to Harris’ border trip by amping up his own rhetoric on immigration. Highlighting violent crimes committed by undocumented immigrants, Trump told a crowd in Walker, Michigan, that Harris “delivered these horrors.”

“She unleashed these atrocities, and blood is on her hands at a level that, probably, nobody’s ever seen in this country,” he said.

Trump also falsely again accused Democrats of letting people enter the country illegally because “they want the votes.” Non-citizens cannot vote in US elections — a reality ignored by Trump, who for years has lied about widespread fraud in the 2020 election.

The Democratic offensive on immigration and border security is an attempt to cut into one of Trump’s clearest-cut political advantages. A CNN poll conducted by SSRS released this week found the former president is trusted by 49% of likely voters to handle immigration, while Harris is trusted by 35%.

Harris on Friday also laid out proposals to strengthen restrictions that have largely barred migrants from seeking asylum in the United States. And she said she would seek paths to citizenship for undocumented immigrants brought into the United States as children.

“They are American in every way. But still, they do not have an earned pathway to citizenship. And this problem has gone unsolved at this point now for decades,” Harris said.

2024 race takes a backseat

The battle over immigration and border security comes at a rare moment this late in a presidential race in which attention has shifted away from both parties’ nominees.

Dozens of people had been killed as Hurricane Helene swept across the Southeast, causing massive flooding. Meanwhile, Israel has escalated its battle with Hezbollah with a strike on a building in Lebanon that it said was storing missiles.

And both parties’ vice presidential nominees are preparing to take center stage next week, as Minnesota Gov. Tim Walz and Ohio Sen. JD Vance meet for their one and only debate Tuesday night.

Fewer than six weeks from Election Day, the 2024 presidential map is still jumbled – with seven battleground states coming into focus.

A new CNN poll conducted by SSRS on Friday showed Harris with a comfortable lead for a single electoral college vote in Nebraska that could have outsized implications.

Nebraska awards one electoral college vote to the winner of each congressional district. The poll of the Omaha-based 2nd District found Harris leading in the state’s most liberal region, with 53% support to Trump’s 42%.

That single electoral vote could be critical if Harris sweeps the “blue wall” of Michigan, Pennsylvania and Wisconsin, but loses the four Sun Belt swing states – Arizona, Georgia, Nevada and North Carolina. That could leave her with 269 electoral college votes – and one more from Nebraska could give her the 270 needed to win the White House.

Another CNN poll conducted by SSRS released Friday found the two candidates tied in North Carolina at 48% each. Trump faces limited paths to victory should he fail to hold North Carolina – the state where he earned his slimmest margin of victory in 2020. And the CNN poll found the scandal-plagued Republican nominee for governor, Lt. Gov. Mark Robinson, far behind his Democratic rival, as the party faces questions about whether Robinson could hurt the overall GOP ticket there in November.

GOP highlights undocumented immigrants’ crime

The Trump campaign and the Republican National Committee on Friday held a press call ahead of Harris’ Arizona visit featuring three mothers of those killed by undocumented immigrants or accidental fentanyl overdose who blamed the vice president for what they described as a lack of accountability on border security.

“This is not a safe time for Americans. Kamala Harris has not acknowledged my daughter’s death,” said Patty Morin, the mother of Rachel Morin, who was raped and killed by a 23-year-old citizen of El Salvador. Rachel Morin was a mother of five herself.

“She is late coming to the table on this. At any point, she could do something,” said southern California mother Anne Fundner, whose 15-year-old son Weston died from a fentanyl overdose.

The call was an effort to cast doubt on Harris’ proposals to tackle border security, as Trump argues that she and President Joe Biden have had four years to do so and have failed.

After a dramatic drop, border crossings are currently at the lowest they’ve been since 2020. US officials have touted back-to-back months of low border crossings, citing recent executive action to curb asylum access at the southern border.

Republicans have labeled Harris the Biden administration’s “border czar,” overstating the president’s more limited 2021 assignment for Harris to tackle the root causes of migration in Central America.

Harris on Friday sought to tap into another part of her resume: Her time as California attorney general. She highlighted efforts to prosecute members of transnational criminal organizations, including traveling to Mexico City with other attorneys general to share intelligence on gangs and cartels.

“Stopping transnational criminal organizations and strengthening our border is not new to me, and it is a long-standing priority of mine,” she said. “I have done that work, and I will continue to treat it as a priority.”

CNN’s Priscilla Alvarez, Ali Main, Ariel Edwards-Levy and Kit Maher contributed to this report.