Hillary Clinton Campaign Doubles Down After Experts Question Claim About ISIS Videos Using Donald Trump

Hillary Clinton's communications director defended her candidate's claim that ISIS is using videos of Donald Trump to recruit members, but could not point to specific evidence of this happening in an interview on "This Week with George Stephanopoulos" today.

Jen Palmieri said Clinton wasn't referring to a specific video during Saturday's debate when she said Trump's anti-Muslim rhetoric is making him "ISIS's best recruiter" and that "they are going to people showing videos of Donald Trump insulting Islam and Muslims in order to recruit more radical jihadists." Clinton offered no specific evidence of the claim.

"She's not referring to a specific video, but he is being used in social media by ISIS as propaganda," said Palmieri.

Many fact checkers and national security experts have been unable to verify Clinton's claim. White House and National Security Council officials would also not support her assertion, telling ABC News they are unaware of any examples of ISIS including Trump in the group's videos.

When asked about the remark following the debate, the Clinton campaign pointed to a comment from an analyst for the SITE Intelligence Group to NBC News. The report did not mention videos, however, and some national security experts dispute the characterization that Trump is being used as a recruitment tool by key ISIS influencers at all.

"We have seen low-level ISIS supporters talk about Trump's remarks but nothing from core-ISIS and its influential supporters," Seamus Hughes, the deputy director of the George Washington University Program on Extremism, told ABC News.

Trump, appearing separately on "This Week," said Clinton "made up" the claims.

"Knowing the Clintons and knowing Hillary, she made it up," he said.

Asked about Trump's remarks, Palmieri referenced his much-disputed claim that there were videos of people cheering in New Jersey after the September 11th attacks.

"What they haven't found is the video Mr. Trump keeps talking about, this alleged mystery video of thousands of people in [New] Jersey cheering the attacks on the World Trade Center," she said. "But it is true that he is being used in social media by ISIS to help recruit."