Vice President Kamala Harris is toughening her position on illegal immigration, taking on hardliner Donald Trump on his signature issue in a series of campaign events and digital ads in coming weeks, according to campaign staff.

The campaign plans to promote Harris' support for a bipartisan border security bill — defeated in the Senate in February after Trump came out against it — that would have increased funding for border agents and detention facilities, an official said.

Harris' more combative approach on immigration is expected to be on display as she campaigns around the country with her running mate Tim Walz, governor of Minnesota, who was chosen in part for his appeal to voters in America's heartland.

Harris will also highlight Trump's most divisive actions, such as his 2018 policy that separated thousands of migrant families at the U.S.-Mexico border and an executive order in 2017 that sought to ban travel from certain Muslim-majority countries. A version of the ban was upheld by the Supreme Court a year later.

A campaign official said Harris had a chance to reintroduce herself to voters after becoming the Democratic presidential candidate following U.S. President Joe Biden's exit from the race last month.

"It's all part of a larger effort by Harris to be direct and to go directly at Trump," said Matt Barreto, a pollster who has worked with the Harris and Biden campaigns. "Democrats always do well when they lean in on the immigration issue and don't run away from it."

The enforcement-first position is a departure from Biden's 2020 campaign, when he pledged a more humane approach to immigration than Trump. Biden gradually hardened his approach as illegal crossings increased.

The Trump campaign has sought to blame Harris for illegal immigration, dubbing her a failed "border czar," though her portfolio was focused on the drivers of migration from Central America.

"If dangerously liberal Kamala is president, our border will remain wide open to terrorists and criminals from around the world who will face no consequence for committing heinous migrant crimes," Trump campaign spokesperson Karoline Leavitt said in a statement when asked about Harris' record.

Harris began setting out her new, more combative strategy in a speech in Atlanta last week, criticizing Trump for helping to sink the border security bill.

She also touted her record on border-related prosecutions as California attorney general.

"I went after transnational gangs, drug cartels, and human traffickers that came into our country illegally," she said. "I prosecuted them in case after case, and I won."

Harris has made the border security bill a centerpiece of her platform, and a digital campaign ad has cast the election as a choice between "the one who will fix our broken immigration system. And the one who's trying to stop her."

Jeffrey Jarman, a Wichita State University professor who focuses on political communication, said Harris' push-back was a way to avoid ceding the issue of border security to Republicans.

"Failure to talk about the issue allows Republicans to completely dominate the discussion and frame her in the most unflattering way," he said.

But he acknowledged that going on the offensive is unlikely to win over Republican voters and that Harris risked getting sidetracked on issues that are not as important to her supporters.

"Candidates who spend too much time talking about the issues of their opponent will always face a more difficult time winning the election," he said.

Numerous polls suggest voters have grown more concerned with high levels of illegal immigration under Biden. In a Reuters/Ipsos poll in May, some 45% of registered voters said immigration has made life harder for native-born Americans.

Illegal crossings have plummeted since Biden issued new restrictions on asylum at the border in June.

A memo published on Friday by the advocacy group Immigration Hub argued that Harris could energize voters if she pairs her enforcement record with protections for immigrants already in the U.S. illegally, citing polling for seven battleground states.

Harris played a key role in the Biden administration's announcement in June that it would provide a path to citizenship to spouses of immigrants in the U.S. illegally, as Reuters previously reported.

Trump has promised mass deportations if reelected.

Ken Budge, the Democrat mayor of the 5,000-person border city of Bisbee, Arizona, said high illegal crossings in recent years have at times made it challenging to provide basic necessities to migrants as they passed through.

He said the Harris campaign wanted to solve the border problem.

"They don't want to just kick the can down the road," Budge said.

Tom Suozzi, a New York Democrat who won a special election to Congress in February by taking a tough stand on the border, said a member of Harris' team texted him a link to her social media ad on immigration last week, saying they thought he would like it.

"A lot of my consultants and a lot of political people were saying, 'What are you talking about immigration for? It's a Republican issue,'" Suozzi said. "I said, 'No, it's an American issue. It's what people are talking about.'"