WEST PALM BEACH, Fla.  — Donald Trump contends he doesn’t know and never even met some of the women accusing him of sexual assault, and his running mate said Friday the campaign is working on producing evidence that the claims are false.

Trump himself has called his accusers “horrible liars” and said he will prove the allegations aren’t true, but Hillary Clinton and ally Michelle Obama say Americans are learning more about Trump’s unacceptable behavior every day.

“We can’t expose our children to this any longer, not for another minute, let alone for four years,” the first lady told Clinton supporters at a rally in New Hampshire. In a passionate address Thursday, Mrs. Obama said that after years of working to end “this kind of violence and abuse and disrespect … we’re hearing these exact same things on the campaign trail. We are drowning in it.”

In an appearance Friday morning on Fox News, Republican vice presidential candidate Mike Pence blamed the news media for what he characterized as an obsession with “unsubstantiated” claims by Trump’s accusers.

“There will be more evidence coming out” to prove Trump’s innocence, Pence said. Asked what evidence he was talking about, Pence said, “The campaign is working on bringing that information out.” He did not elaborate.

Trump was cheered at rallies Thursday in Florida and two appearances in Ohio, states central to his campaign. He is campaigning Friday in another crucial state, North Carolina.

Clinton has no rallies planned Friday, but President Barack Obama planned to campaign for her in Ohio.

The allegations against Trump dominated the campaign Thursday. Four women have told publications detailed stories about encounters with Trump that ended with groping, kissing and other unwanted sexual advances.

“These vicious claims about me, of inappropriate conduct with women, are totally and absolutely false. And the Clintons know it,” Trump said Thursday in Florida. He offered no evidence discrediting the reports except to ask why his accusers had waited years and then made their allegations less than a month before the election.