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 Monday ramped up his attacks on 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 investigation, calling it a "national disgrace."

"Disgraced and discredited Bob Mueller and his whole group of Angry Democrat Thugs spent over 30 hours with the White House Councel [sic], only with my approval, for purposes of transparency," Trump tweeted early Monday morning.

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"Anybody needing that much time when they know there is no Russian Collusion is just someone looking for trouble," he continued. "They are enjoying ruining people’s lives and REFUSE to look at the real corruption on the Democrat side — the lies, the firings, the deleted Emails and soooo much more! Mueller’s Angry Dems are looking to impact the election."

"They are a National Disgrace!" the president added.

Disgraced and discredited Bob Mueller and his whole group of Angry Democrat Thugs spent over 30 hours with the White House Councel, only with my approval, for purposes of transparency. Anybody needing that much time when they know there is no Russian Collusion is just someone.... — Donald J. Trump (@realDonaldTrump) August 20, 2018

....looking for trouble. They are enjoying ruining people’s lives and REFUSE to look at the real corruption on the Democrat side - the lies, the firings, the deleted Emails and soooo much more! Mueller’s Angry Dems are looking to impact the election. They are a National Disgrace! — Donald J. Trump (@realDonaldTrump) August 20, 2018

Trump in a subsequent tweet said Mueller's team "made up a phony crime called Collusion."

"Where’s the Collusion?" he asked. "They made up a phony crime called Collusion, and when there was no Collusion they say there was Obstruction (of a phony crime that never existed). If you FIGHT BACK or say anything bad about the Rigged Witch Hunt, they scream Obstruction!"

Where’s the Collusion? They made up a phony crime called Collusion, and when there was no Collusion they say there was Obstruction (of a phony crime that never existed). If you FIGHT BACK or say anything bad about the Rigged Witch Hunt, they scream Obstruction! — Donald J. Trump (@realDonaldTrump) August 20, 2018

Trump on Sunday tweeted multiple times about Mueller's probe into possible ties between his presidential campaign and Russia, calling the investigation "McCarthyism at its worst."

"Study the late Joseph McCarthy, because we are now in period with Mueller and his gang that make Joseph McCarthy look like a baby!” the president tweeted, referring to former Sen. Joseph McCarthy's (R-Wis.) search for communists in the 1950s.

Study the late Joseph McCarthy, because we are now in period with Mueller and his gang that make Joseph McCarthy look like a baby! Rigged Witch Hunt! — Donald J. Trump (@realDonaldTrump) August 19, 2018

The president on Sunday also doubled down on his talking point that Mueller should investigate former Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonFox News poll: Biden ahead of Trump in Nevada, Pennsylvania and Ohio Trump, Biden court Black business owners in final election sprint The power of incumbency: How Trump is using the Oval Office to win reelection MORE.

Trump has become increasingly irate over the Russia investigation, according to multiple reports. He continually calls the probe a "witch hunt" and insists there was "no collusion."