It’s a bid to entice a handful of Senate Republicans to join their push for new documents and witnesses involved in the president’s Ukraine scandal, particularly those who have expressed dismay with Senate Majority Leader Mitch McConnell’s vow to coordinate closely with the White House.

It’s also a long-shot appeal to Trump, who maintains he’s done nothing wrong and had a “perfect” call with Ukrainian President Volodymr Zelensky when he asked for a probe of former Vice President Joe Biden.

Trump has said he wants to hear from his own array of witnesses in the trial. Democrats hope his efforts to clear himself translate to Republican senators agreeing to seek testimony from figures like acting White House chief of staff Mick Mulvaney and former national security adviser John Bolton.

“What if we get them and some of them exonerate the president one way or another?” asked Senate Minority Leader Chuck Schumer in a recent interview.