By Jeremy Herb and Manu Raju, CNN/StyleMagazine.com

Donald Trump's former attorney and fixer Michael Cohen testified in detail Wednesday about the President's involvement in hush-money payments to women and his knowledge of longtime confidant Roger Stone's efforts to contact WikiLeaks, while Trump's Republican defenders aggressively worked to undermine Cohen's credibility.

Cohen's dramatic public testimony before the House Oversight Committee ping-ponged between Democrats who walked Cohen through the actions Trump took and Republicans who challenged Cohen over his financial crimes and past lies to Congress.

Cohen's public testimony Wednesday was undoubtedly a spectacle, but its ultimate impact will depend upon whether Cohen's allegations are viewed as credible.

Cohen's hearing comes while the President has his own big moment: Cohen is testifying about what he says are Trump's misdeeds while the President is in Vietnam meeting with North Korean leader Kim Jong Un.

Cohen also revealed that prosecutors in New York are investigating conversations between Trump and Cohen that occurred after Cohen's office was searched by the FBI in April 2018.

In his testimony, Cohen explained how Trump instructed him to pay $130,000 to Stormy Daniels during the 2016 campaign for her silence about an alleged affair with Trump, which Trump denies. Trump then reimbursed Cohen as President for the payments, Cohen said — and he provided a copy of the check to show it.

Cohen told the committee that there was "no doubt in his mind" that Trump knew he was paying Cohen for "hush money payments."

In his opening statement, Cohen launched a broadside against Trump, accusing him of being "a racist," "a conman" and "a cheat."

Cohen also talked about how Trump discussed the Trump Tower Moscow project with him into the 2016 campaign — the topic that Cohen would ultimately lie to Congress about — and that Trump had knowledge of Stone's efforts to reach out to WikiLeaks ahead of the release of hacked Democratic emails during the 2016 campaign.

"The last time I appeared before Congress, I came to protect Mr. Trump. Today I am here to tell the truth about Mr. Trump," Cohen said.

Republicans attack Cohen's credibility

Republicans pressed Cohen repeatedly on the crimes he pleaded guilty to, arguing he had no credibility having previously lied to Congress and that his own financial crimes — which he pleaded guilty to along with the campaign finance violations — had nothing to do with Trump.

Ohio Rep. Jim Jordan, the top Republican on the Oversight Committee,accused Cohen of turning against Trump after he did not get a job at the White House.

"You wanted to work in the White House, you didn't get brought to the dance," Jordan said.

"I was extremely proud to be the personal attorney for the President of the United States of America. I did not want to go to the White House," Cohen responded.