Sen. Lindsey Graham (R-SC) has invited Donald Trump lawyer Rudy Giuliani to appear in front of the Senate Judiciary Committee to present information he claims to have dug up in Ukraine—even though the details of Giuliani’s self-directed investigation raise serious doubts about the credibility of any information he presents.

“Rudy, if you want to come and tell us what you found, I'll be glad to talk to you,” Graham said in an interview for CBS’ Face the Nation set to air Sunday. “I don’t know what Rudy found, I don’t know what he was up to when he was in the Ukraine.”

Giuliani traveled to Hungary and Ukraine earlier this month with a camera crew from One America News, a pro-Trump cable network that has eagerly courted the president’s approval in its rivalry against Fox News. Giuliani and OAN White House reporter Chanel Rion interviewed former Ukrainian prosecutors who repeated widely debunked claims that former Vice President Joe Biden pressured the Ukrainian government to drop investigations into a Ukrainian energy company that had hired his son to sit on its board.

While Giuliani told Trump he had uncovered “plenty” on his Ukraine dirt-digging mission, his sources alone have raised red flags. Several of Giuliani’s witnesses are widely seen as discredited in Ukrainian circles, while OAN reporter Rion is a conspiracy theorist whose botched reporting on another story recently prompted a retraction from her network.

OAN has had other questionable ties to Ukraine. The network tried to get a United States visa for a Ukrainian millionaire who had promised dirt on the Biden family. Before that could happen, though, the millionaire was arrested on a warrant issued by Ukrainian anti-corruption prosecutors. He’d been wanted on embezzlement charges for years and was accused of treason.

Graham’s offer also comes as Giuliani is reportedly the subject of multiple federal investigations aimed at his foreign ties. Two Giuliani associates involved in his Ukraine crusade are facing campaign finance charges.

Giuliani, who was spotted at the White House on Friday, claims that he returned from Ukraine with a suitcase full of documents about the Bidens. Graham said he’s open to hearing from Giuliani at a hearing separate from impeachment.

“We can look at what Rudy's got and Joe Biden, Hunter Biden and anything else you want to look at after impeachment,” Graham said in his Face the Nation appearance. “But if Rudy wants to come to the Judiciary Committee and testify about what he found, he's welcome to do so.”