The White House counsel to former President Nixon, John Dean, took aim at President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE hours after Trump's former longtime lawyer took a plea deal with federal prosecutors.

“I think we’ve established today that we have a criminal president, and that is historic,” Dean told Bloomberg on Tuesday, shortly after Cohen pleaded guilty to charges of bank fraud, tax fraud and campaign finance law violations in a courtroom in New York.

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“It’s a big day, it’s a bad day,” added Dean, who was a key witness in the Watergate scandal after pleading guilty to a single count of obstruction of justice.

Cohen said he broke campaign finance laws "in coordination and at the direction of a candidate for federal office," indirectly referencing Trump.

He pleaded guilty to violating campaign finance law by making payment arrangements for adult-film star Stormy Daniels and former Playboy model Karen McDougal in efforts to keep their allegations of affairs with Trump quiet in the months before the 2016 presidential election.

The development surrounding Trump’s former lawyer, who once said he would “take a bullet” for the president and was one of his closest associates, came the same day the president’s former campaign chairman, Paul Manafort Paul John ManafortOur Constitution is under attack by Attorney General William Barr Bannon trial date set in alleged border wall scam Conspicuous by their absence from the Republican Convention MORE, was found guilty on eight charges of bank and tax fraud by a jury in Virginia.

Trump has since accused Cohen of making up stories to "get a 'deal'" and said in a tweet that he has "such respect" for Manafort because he did not "break" like Cohen by providing prosecutors with damaging information.