WASHINGTON (CN) – A federal judge agreed Thursday to delay sentencing for Trump campaign adviser Rick Gates until January as he continues to cooperate with Special Counsel Robert Mueller’s investigation of Russian meddling in the 2016 election.

Gates pleaded guilty in February to conspiracy against the United States and making false statements to the FBI. He was also a key witness in the bank and tax fraud trial against President Donald Trump’s former campaign chairman Paul Manafort in August.

Gates’ continued cooperation with Mueller comes amid renewed calls by the president to end the special counsel’s investigation.

Trump spent much of Thursday morning lobbing relentless critiques of Mueller on Twitter and offering assurances that things in the White House are “running very smoothly.”

The forced resignation of Attorney General Jeff Sessions, the controversial appointment of Matt Whitaker as acting attorney general, and rumors of an impending staff shakeup in the West Wing, have all been the subject on intense scrutiny in recent days.

The state of Maryland challenged Whitaker’s appointment in federal court on Tuesday, and that prompted the Justice Department’s Office of Legal Counsel to release a memo justifying the president’s decision.

Still, Democrats in Congress and others are calling for Whitaker to recuse himself from overseeing the Mueller investigation, citing past statements he’s made criticizing the investigation and suggesting ways to effectively starve it out of existence.

And those persistent calls appeared to have stoked Trump’s animus for the investigation Thursday morning. In a series of tweets, the president called Mueller’s effort a “TOTAL WITCH HUNT LIKE NO OTHER IN AMERICAN HISTORY!” [Emphasis original.]

“The inner workings of the Mueller investigation are a total mess,” the president continued. “They have found no collusion and have gone absolutely nuts. They are screaming and shouting at people, horribly threatening to come up with the answers they want. They are a disgrace to the Nation and don’t … care how many lives the [sic] ruin.”

Trump continued: “These are Angry People including the highly conflicted Bob Mueller who worked for Obama for 8 years. They won’t even look at all the bad acts and crimes on the other side.”

The president also aired his frustration over the criticism of Whitaker’s appointment, saying, “Universities will someday study what highly conflicted (and NOT Senate approved) Bob Mueller and his gang of Democrat thugs have done to destroy people.”

Trump then went on to suggest Mueller is “protecting Crooked Hillary, Comey, McCabe, Lisa Page & her lover, Peter S, and all of his friends on the other side.”

The “only Collusion” occurring is between “Democrats with Russia and many others,” the president wrote.