Democratic presidential candidate Kamala Harris defended the Biden administration's handling of illegal immigration in a combative television interview on Wednesday, blaming Republicans for failing to pass a border security bill.

Grilled by host Bret Baier on Fox News, Harris also defended President Joe Biden's mental fitness, her years as his vice president and her previous support of gender-affirming surgery for transgender inmates.

Harris and Baier frequently talked over each other and Harris grew visibly frustrated, but she delivered her message for the Nov 5 election to a conservative audience that might not often hear it.

She was asked to defend the administration's early decision to reverse some of the restrictive border policies of Republican rival Donald Trump when he was president, and to respond to a mother who testified in Congress about the loss of her daughter at the hands of an immigrant in the US illegally.

"I'm so sorry for her loss, but let's talk about what is happening right now," Harris said. She said Trump told Republicans to reject a bipartisan immigration bill early this year because "he preferred to run on a problem instead of fixing a problem."

Trump and Republicans have claimed that immigrants are fuelling violent crime in the United States, although studies show immigrants commit crimes at lower rates than others.

Asked about her recent comment that there was "not a thing" she would change about the actions of the Biden administration, Harris said, “Let me be very clear, my presidency will not be a continuation of Joe Biden's presidency."

She said she would bring in new ideas from Republicans and business leaders to solve housing shortages and expand small businesses.

Trump team calls interview 'train wreck'

Harris was a vocal supporter of Biden when he faced mounting questions about his mental fitness after a disastrous June debate with Trump, before dropping out of the race in July. She was asked to defend those statements.

Biden has the “judgment” and “experience” to be president, she said, while questioning Trump’s fitness for office. “Joe Biden is not on the ballot, and Donald Trump is,” Harris said.

She was pressed on her position on using taxpayer funds for gender-affirming surgery for transgender inmates, including those who are undocumented. Trump has spent millions of dollars in ads on the subject in battleground states.

“I will follow the law,” Harris said, noting that the U.S. Bureau of Prisons provided gender-affirming treatments under Trump. She accused him of “throwing stones when you live in a glass house.”

The nearly 30-minute interview marked the first time Harris has appeared as a presidential candidate on the conservative media network, which often features opinion show hosts who mock her and other Democrats and tout Trump's policies.

Within minutes of the interview's end, the Trump campaign released a statement calling it a "train wreck."

David Urban, a political strategist and past Trump campaign aide, said Harris gave an uneven and subpar performance, avoiding responsibility and making Trump the scapegoat. "Another losing media cycle for the Harris campaign," Urban said.

Democrats said Harris went on unfriendly territory and made it through without any gaffes. Repeated interruptions kept Harris's answers short, they said, preventing the meandering answers that she has been criticized for in the past.

“We feel like we definitely achieved what we set out to achieve," said Brian Fallon, a Harris spokesperson. "She was able to reach an audience that has probably been not exposed to the arguments she’s been making on the trail, and she also got to show her toughness in standing tall against a hostile interviewer."

Courting Republicans

The interview was part of a direct appeal by Harris on Wednesday to Republican voters. Before the Fox News interview, she highlighted Republican support for her campaign in a pivotal county in Pennsylvania, one of the handful of swing states likely to determine the election.

In Bucks County outside of Philadelphia, Harris emphasized Trump's attempt to overturn his election loss four years ago, when he lost the White House to Biden.

She said Trump's actions violated the US Constitution and that, if given the chance, he would violate it again.

"He refused to accept the will of the people and the results of a free and fair election. He sent a mob, an armed mob, to the United States Capitol, where they violently assaulted police officers, law enforcement officials and threatened the life of his own vice president," Harris said.

Over 100 Republicans joined Harris in Bucks County, including Adam Kinzinger, a former congressman and member of the committee that investigated the Jan. 6 attack on the Capitol by supporters of then-President Trump.

"No matter your party, no matter who you voted for last time, there is a place for you in this campaign," Harris said. She led Trump by a marginal 46% to 43% in a recent Reuters poll.

Trump on Wednesday participated in a town hall for Latino voters hosted by the Spanish-language network Univision. Fox News aired another Trump town hall with an all-women audience.

Harris has previously sought to court voters disillusioned by Trump. Former Republican congresswoman Liz Cheney, daughter of former Vice President Dick Cheney, this month urged voters to put country over party and vote for Harris, saying Trump was not fit to lead the US.

Biden beat Trump in Bucks County by about 17,000 votes in the 2020 election, while former Secretary of State Hillary Clinton beat Trump there in 2016 by fewer than 3,000 votes, according to county data.

This summer, Republicans overtook Democrats in the number of voter registrations in Bucks County for the first time in a generation. Republicans now have some 3,500 more voters in the county than Democrats, according to the latest data.

Harris is also weighing joining the podcaster Joe Rogan, whose show reaches millions of men across the political spectrum, and who has joked that a "puppet master" was behind Harris' strong debate performance against Trump last month.