Democratic White House nominee Kamala Harris has conducted her first-ever interview with Fox News, clashing repeatedly with the host on transgender prisoners, illegal immigration and President Biden’s mental fitness.

During the combative 25-minute sit-down, the US vice-president and Bret Baier frequently interrupted each other, with Harris at one point saying: “I’m in the middle of responding to the point you’re raising and I’d like to finish.”

Her foray on to a network that hosts some of her most vocal media critics comes as opinion polls show a majority of male voters back her Republican rival, Donald Trump, ahead of next month’s election and that this gender gap is even eating into her core electoral coalition, including younger voters, blacks and Hispanics.

Trump, meanwhile, appeared on Fox on Wednesday, in a town hall-style event with an all-female audience as he worked to tackle his own political vulnerability with women voters.

The vice-president’s interview began on the subject of immigration, with Baier playing her an emotional clip showing the mother of Jocelyn Nungaray, a 12-year-old girl killed by a migrant who had illegally crossed the border into the US and was released from detention.

Asked whether she should apologise to the families of Americans who were killed by illegal migrants, Harris responded: “I’m so sorry for her loss.”

“Those are tragic cases,” she added. “There’s no question about that.”

Baier also asked about her 2019 stance that border crossings should be decriminalised. This is one of several issues where the vice-president has been accused of flip-flopping.

Harris said: “I do not believe in decriminalising border crossings and I have not done that as vice-president, and I would not do that as president.”

She went on to blame Trump for persuading Republicans in Congress to vote down a border deal earlier this year, saying: “He preferred to run on a problem instead of fixing a problem.”

• US election polls: Who is ahead – Harris or Trump?

Harris was asked about taxpayer-funded gender reassignment surgery for prisoners, a policy she has in the past said she supports.

Asked if she would as president advocate for taxpayer dollars to be used to that end, she responded: “I will follow the law.”

When pressed for more details, she said such surgeries had been available to prisoners during while Trump was in office.

However, no transgender surgeries took place in the federal prison system while Trump was president.

The Federal Bureau of Prisons told BBC Verify that two federal inmates have had gender reassignment operations – the first in 2022 and the second in 2023.

When Harris was running as a Democratic candidate for president in 2019, she checked a box in a questionnaire from a civil rights group saying that as president, she would use her authority to ensure that transgender-identifying detainees in prison and immigration facilities would have access to “treatment associated with gender transition, including all necessary surgical care”.

The Harris campaign has said this “is not what she is proposing or running on” in the 2024 election.

After Fox played a clip from an interview she gave last week saying that there’s “not a thing” she would change about the actions of the Biden-Harris administration, Harris went further than she has gone before in trying to place some distance between herself and her boss.

“Let me be very clear, my presidency will not be a continuation of Joe Biden’s presidency,” she said on Wednesday, without elaborating.

Baier pressed Harris on her belief that American voters do not want to “go back” to Trump, and whether people that continue to support the former president are “stupid” or “misinformed”.

“I would never say that about the American people,” Harris responded.

Baier also pressed her on why one of her campaign promises is to “turn the page” when she has been vice-president for more than three years.

Harris turned to criticising Trump.

Harris deflected questions from Baier concerning Biden’s mental state.

Asked when she first noticed that Biden’s mental faculties “appeared diminished”, Harris said: “Joe Biden, I have watched in from the Oval Office to the Situation Room, and he has the judgment… and experience to do exactly what he has done in making very important decisions on behalf of the American people.”

When pressed further on the issue, Harris responded: “Joe Biden is not on the ballot, and Donald Trump is.”

• SIMPLE GUIDE: How to win a US election
• EXPLAINER: What Harris or Trump would do in power
• ANALYSIS: Would Trump tariffs hurt US consumers?
• ON THE GROUND: Is Harris support in Michigan slipping?
• VOICES: ‘I’m uneasy’ – first-time voters weigh in