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 on Sunday ripped Democrats ahead of testimony from John Dean, a former White House counsel for President Nixon who proved pivotal during the Watergate scandal.

"The Dems were devastated — after all this time and money spent ($40,000,000), the Mueller Report was a disaster for them," Trump tweeted Sunday evening.

"But they want a Redo, or Do Over. They are even bringing in @CNN sleazebag attorney John Dean. Sorry, no Do Overs — Go back to work!"

....No Obstruction. The Dems were devastated - after all this time and money spent ($40,000,000), the Mueller Report was a disaster for them. But they want a Redo, or Do Over. They are even bringing in @CNN sleazebag attorney John Dean. Sorry, no Do Overs - Go back to work! — Donald J. Trump (@realDonaldTrump) June 9, 2019

Dean, a CNN contributor, was connected to the Watergate cover-up and delivered televised testimony before lawmakers that helped lead to Nixon’s resignation.

Democrats in the House Judiciary Committee will grill Dean on Monday in an attempt to shine a spotlight on the unsavory details about Trump’s conduct contained in special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE’s report.

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Dean has been a vocal critic of Trump's, arguing the president engaged in obstruction based on what is described in Mueller’s report.

Mueller's team did not make a judgement on obstruction of justice, instead listing 10 potential cases of it.

Many Democrats have argued Mueller found substantial evidence that Trump obstructed justice and have taken the special counsel's public statements on May 29 as a green light to further investigate the president’s conduct.

Democrats have said they hope Dean will be able to provide firsthand expertise on obstruction of justice and to compare Trump's conduct with Nixon's.

Trump has frequently painted Democrats as trying to defame him ahead of the 2020 presidential election, saying that Mueller's report made it clear that there was "no collusion, no obstruction."