Sen. Lindsey Graham (R-S.C.) on Sunday, Dec. 14, invited President Donald Trump’s personal attorney—Rudy Giuliani—to testify about his recent travels to Ukraine, while reacting to an attack on him by former Vice President Joe Biden.

Graham, during an appearance on CBS News’s “Face the Nation” noted that Giuliani could testify before the Judiciary Committee but should not coincide with the upcoming Senate impeachment trial.

“We can look at what Rudy’s got and Joe Biden, Hunter Biden, and anything else you want to look at after impeachment,” Graham told host Margaret Brennan. “But if Rudy wants to come to the Judiciary Committee and testify about what he found, he’s welcome to do so.”

Giuliani gained attention after emerging as a key player in the Democrat-led House impeachment inquiry, with his recent trip to Ukraine to meet with numerous former and current officials to further investigate the president’s political rivals, including Biden.

When Brennan played a clip of Biden accusing President Trump of “holding power over him that even the Ukrainians wouldn’t yield to” and saying that Graham “is about to go down in a way that I think he’s going to regret his whole life,” Graham immediately dismissed these claims.

“Oh no, not at all,” Graham said, referring to Biden as “a friend.”

But when it comes to the Biden family’s Ukraine dealings, Graham said, “The whole process … reeks with politics.”

“Now that you want to talk about Ukraine, it’s pretty hard for me to go home and tell my constituents to ignore the fact that Hunter Biden received fifty thousand dollars a month from a gas company in the Ukraine, run by the most corrupt person in the Ukraine,” Graham explained. “And two months after the gas company was investigated, the prosecutor got fired.”

“I don’t know if there’s anything to this. I hope not,” Graham continued. “I hope I can look at the transcripts of the phone call between Biden in the Ukraine—Joe Biden after the investigation began and say there’s nothing there. These are legitimate concerns about what happened in the Ukraine. I love Joe Biden, but none of us are above scrutiny. I’d like to knock all this off and get back on governing the country.”

Biden is notoriously sensitive when questioned about his—and his son Hunter’s—dealings in Ukraine and has often forcefully rejected allegations of wrongdoing.

However, Hunter Biden himself had acknowledged his “poor judgment” on taking the lucrative position at Ukrainian gas company Burisma Holdings.

“In retrospect I think there was poor judgment on my part,” Hunter Biden said during an Oct. 15 ABC News interview recorded at his Los Angeles residence. “I know I did nothing wrong at all, but it was poor judgment to be in the middle of something that is a, it’s a swamp in many ways.”