Presidential candidate Kamala Harris and other Democrats have gone on the offensive as tough on immigration and border security, running on an issue Republicans for years have featured as a main policy weakness of the Biden administration.

A new TV ad from the Harris campaign highlights the presumptive Democratic nominee’s background as a prosecutor, making use of her time as district attorney of San Francisco and California attorney general.

“As vice president, she backed the toughest border control bill in decades,” a narrator states on the video. “And as president, she will hire thousands more border agents and crack down on fentanyl and human trafficking. Fixing the border is tough. So is Kamala Harris.”

The ad builds on remarks Harris gave at a rally last week in Glendale, Ariz., where she told the estimated 15,000 supporters that her record as a prosecutor showed she would be tough on the issue.

“I was attorney general of a border state. I went after the transnational gangs, the drug cartels and the human traffickers,” Harris said. “I prosecuted them in case after case and I won, so I know what I’m talking about.”

At the same time, Harris said her approach to immigration would be multi-faceted and not leave undocumented immigrants completely in the lurch, pleading to pursue policy that “includes strong border security and an earned pathway to citizenship.”

Meanwhile, the Harris campaign has pointed to the current administration policies as working. A statement from the campaign on Monday draws on Customs and Border Protection numbers, touting how border crossings having dropped for five straight months as well as the apprehension of “two of Mexico’s most notorious and dangerous drug lords.”

Those five months line up with the new restrictions on asylum President Joe Biden implemented in May and the arrest of Ismael “El Mayo” Zambada, co-founder of the Sinaloa Cartel, and Joaquin Guzman Lopez, the son of Zambada’s former partner Joaquin “El Chapo” Guzman.

Harris’ move comes as Trump and Republicans have pivoted to framing her as the Biden administration’s “border czar” and largely responsible for the administration’s immigration policies, as they put the issue at the forefront in the race for the White House.

States such as Arizona and Nevada, which are directly affected by illegal immigration, are battleground states that could shape the outcome of the presidential race. The Harris campaign spent $1.56 million to air the TV ad in eight states where polling is tight, two of which are Arizona and Nevada, according to data from AdImpact.

Republicans still appear to have an advantage over Democrats on the immigration issue. A Marquette Law School poll conducted late last month found likely voters believe Trump will be better than Harris on immigration by a 13-point margin.

The House GOP, just before Congress left town for the summer, passed a resolution that sought to link Harris to the fentanyl crisis and stories of crime associated with migrants coming across the border. Six Democrats, either from moderate districts or districts near the southern border, joined Republicans on that vote.

Rep. James R. Comer of Kentucky, chairman of the House Oversight and Accountability Committee, said on Fox News on Sunday that he would probe Harris’ record on immigration, including requests for documents from U.S. Customs and Border Patrol on its correspondence with the vice president’s office.

“I don’t think anything Kamala Harris would say with respect to the southern border should have credibility with the American people, because this administration not only failed at the southern border, they, in my opinion, willfully sent an invitation to people all across the world to cross that border,” Comer said on “Sunday Night in America with Trey Gowdy.”

Donald Trump, speaking with Elon Musk in a high-profile conversation on X Space on Monday night, criticized Harris for not doing enough on the U.S. southern border.

“She was the border czar, and you people allow them to get away with their disinformation campaign,” Trump said. “Now she’s trying to say that she wasn’t — she wasn’t really involved, and the whole thing is horrible. She was totally in charge. She could have shut the border down without [Biden].”

Democrats say that title is inaccurate, and her role was limited to identifying root problems of the issues bringing migrants into the United States from Central America.

A key point in the Harris ad and from Democrats is the failure of the bipartisan border deal. Vice presidential nominee Tim Walz has pointed to that Senate compromise bill as key to a Harris plan to stop illegal immigration.

Democrats say the legislation would be crucial to stemming the flow of migrants across the border, while critics say the measure would make things worse. Democrats have blamed Trump for killing the legislation.

Transportation Secretary Pete Buttigieg, making an appearance on “The View” earlier this month, said the rejection of the border security bill at the behest of Trump demonstrates Republicans want to do nothing about immigration.

“It’s not just that he doesn’t want a leader that he disagrees with to get credit,” Buttigieg said. “He doesn’t want America to solve that problem because the worse that problem is in America the better it is for Donald Trump.”

Comer said the bill was introduced three years into the Biden-Harris administration. “There had already been tens of millions of illegals pour across our country. They did nothing to halt the flow,” Comer said Sunday on Fox News.

At least one other Democrat is following suit in taking on a tough immigration stance.

Michelle Vallejo, a Democratic candidate for a U.S. House seat in Texas, says in a TV ad that came out Tuesday that her family was able to achieve in the “Sueño Americano” in Texas, but at the same time expressed the need to “get serious about finding solutions to the chaos at our border.”

“As the next congresswoman from Texas’ 15th congressional district, I am ready to work with both Democrats and Republicans to secure our border,” Vallejo says. “We deserve better than an extremist who is using our home for her own personal benefit, and I have never been more confident that by working on real solutions for our community, we will win this November.”

Rep. Tom Suozzi, D-N.Y., said Tuesday on CNN that Harris and other Democrats should be talking about securing the border while campaigning. “I mean, the best politician, the best elected official, is the one who says what the people are thinking already, and people are talking about the border. That’s a real issue,” Suozzi said.