Donald Trump Jr. has blasted Michael Cohen, questioning his motives for testifying before the House Oversight and Reform Committee on Wednesday.

Cohen, the ex-Trump fixer who has been sentenced to three years in prison, unloaded on President Trump during his testimony by repeatedly saying he was “ashamed” of his past work for Trump, while also claiming he had “suspicions” -- though no evidence -- regarding whether Trump's presidential campaign coordinated with Russia in 2016.

Cohen began his testimony saying of Trump: “He is a racist. He is a conman. And he is a cheat.” After outlining numerous alleged misdeeds by Trump, Cohen expressed regret and repeated the refrain “yet I continued to work for him.”

MICHAEL COHEN CONDEMNS TRUMP AT HEARING: 'HE IS A RACIST. HE IS A CONMAN. AND HE IS A CHEAT.'

Cohen came to the hearing with a slew of exhibits, including checks that he said are proof of his previous claims that Trump organized hush-money payments to two women who claimed affairs with Trump during the campaign.

But Trump Jr. was not swayed by any of the comments or exhibits, and instead unloaded on Cohen in a series of tweets.

“And that’s what all this is about. Cohen just wants to be famous. He always wanted his own TV show and the limelight and when he couldn’t get it one way he had to try another,” Trump Jr. tweeted.

He earlier mocked Cohen by writing: “This sounds like a breakup letter... and I’m keeping your sweatshirt.”

In his testimony, Cohen claimed President Trump previously told him and others that Trump Jr.: "had the worst judgment of anyone in the world."

Earlier, the much-awaited hearing began with fireworks, as Republicans portrayed Cohen as a liar and unsuccessfully moved to postpone the hearing while Democratic Chairman Elijah Cummings accused the GOP of trying to suppress the testimony.

RNC TELLS MICHAEL COHEN TO ‘HAVE FUN IN PRISON,’ AS GOP READIES WAR ROOM TO PUSH BACK ON TESTIMONY

In his opening statement, Cummings acknowledged that Cohen “repeatedly lied in the past,” calling it an “important factor we need to weigh.” He said if Cohen doesn’t tell the truth, he’ll refer him to the Justice Department for prosecution.

But Cummings said the hearing is important for understanding the president’s past actions, adding, “the days of this committee protecting the president at all costs are over.”

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Ohio GOP Rep. Jim Jordan, the ranking member on the committee, in his opening statement ripped Democrats for calling Cohen to testify, emphasizing Cohen’s guilty plea to previously lying to Congress. Jordan went on to accuse Democrats of holding the hearing so they can later try to impeach the president.

“The first announced witness for the 116th Congress is a guy who is going to prison in two months for lying to Congress,” Jordan said.

Fox News' Alex Pappas contributed to this report.