Former Vice President Joe Biden Joe BidenCast of 'Parks and Rec' reunite for virtual town hall to address Wisconsin voters Biden says Trump should step down over coronavirus response Biden tells CNN town hall that he has benefited from white privilege MORE said Thursday that he doesn’t "know what happened” to Sen. Lindsey Graham Lindsey Olin GrahamThe Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters Senate Democrats' campaign arm announces seven-figure investment to boost Graham challenger Graham: Comey to testify about FBI's Russia probe, Mueller declined invitation MORE (R-S.C.), adding that they are friends and Graham pushing for an investigation into his son Hunter Biden has been a "disappointment."

Joe Biden, a 2020 presidential candidate, made the comments on ABC's "The View" about a week after the Senate voted to acquit President Trump Donald John TrumpHR McMaster says president's policy to withdraw troops from Afghanistan is 'unwise' Cast of 'Parks and Rec' reunite for virtual town hall to address Wisconsin voters Biden says Trump should step down over coronavirus response MORE of the two impeachment articles approved in the House. The House impeachment was centered around Trump's push for Ukraine to announce a probe of the Bidens over unfounded allegations of corruption.

"I don't know what happened."

Joe Biden discusses his past friendship with Sen. Lindsey Graham and calls it a “disappointment” that the senator is supporting an investigation into his son, Hunter Biden: “Some things you have to do aren’t worth the job.” https://t.co/2Y3udLFCSB pic.twitter.com/xRvo7lFQ1b — The View (@TheView) February 13, 2020

Graham, a top Trump ally, has supported efforts to investigate matters related to the Bidens and Ukraine. He first disclosed on Sunday that the Justice Department had created a process in which it could review information on Ukraine from Trump's personal attorney, Rudy Giuliani Rudy GiulianiGrand jury adds additional counts against Giuliani associates Lev Parnas and and Igor Fruman Juan Williams: Breaking down the debates Giuliani criticizes NYC leadership: 'They're killing this city' MORE.

ADVERTISEMENT

Asked about Graham's position, Biden said that he, Graham and the late Sen. John McCain John Sidney McCainThe electoral reality that the media ignores Kelly's lead widens to 10 points in Arizona Senate race: poll COVID response shows a way forward on private gun sale checks MORE (R-Ariz.) used to travel a lot together while they were all in the Senate.

"I don't know what happened," he said, "because the way he dealt with the attacks on John after he passed away ... I don't know what happened."

Asked if Graham's actions were part of a reelection strategy, Biden said, "I think that's it but it even surprises me."

"Look, some things you have to do aren't worth the job," he said. "I have to admit it's a disappointment, but it is what it is and there's nothing there. This is all to try make it sound like Trump had some rationale for doing what he did. He violated the Constitution. Every single person who testified acknowledged he did that and now they say it doesn't matter that you violate the Constitution. He just weaponized the presidency."

ADVERTISEMENT

House Democrats argued that Trump's dealings with Ukraine amounted to a clear abuse of power and that he was unfit for office. But Trump and his GOP allies have repeatedly contended that the president was concerned with rooting out corruption when he brought up the Bidens in a call with the Ukrainian president.

To defend the stance, they've seized on Hunter Biden's work for a Ukrainian gas company while Biden served as vice president. Hunter Biden sat on the board of Burisma as Biden pushed for the dismissal of a Ukrainian prosecutor. There is no evidence that either Biden committed any wrongdoing.

Graham said Sunday that he continued to think “questions about the conflict of interest regarding Hunter Biden in Ukraine need to be asked."

Joe Biden has repeatedly denounced Trump's push for an investigation of him as an effort to "destroy" him and his family. He said on "The View" that he's found it particularly "hurtful" seeing Graham support the efforts.

But he said that the South Carolina senator remained a friend, saying that "presidents can't hold grudges."

Biden's appearance on "The View" came after poor showings in the first two states of the Democratic primary season. Biden, who had led many national polls heading into the year, placed in fourth in Iowa and fifth in New Hampshire.