President Trump stops to talk to members of the media as he walks to board Marine One and depart from the South Lawn of the White House last month. (Jabin Botsford/The Washington Post)

President Trump on Thursday lashed out anew at the investigation of special counsel Robert S. Mueller III, calling his team of lawyers “a disgrace to our Nation” and accusing them, without evidence, of threatening witnesses to get answers they want.

Trump’s rant, in a pair of morning tweets, came a week after the installation of Matthew G. Whitaker as acting attorney general, a move many Democrats have said appears designed to curtail Mueller’s investigation into possible coordination between Russia and Trump’s campaign during the 2016 election.

Trump angrily dismissed a reporter’s question about that notion last week and said he had not spoken to Whitaker about the Russia probe before naming him to replace ousted attorney general Jeff Sessions.

Many of Trump’s complaints in Thursday’s tweets were familiar, but they took on heightened significance with Whitaker now overseeing Mueller’s probe, which is also examining whether Trump has obstructed justice.

The tweets also come as Trump spend time with his personal legal team this week to prepare written answers to questions from Mueller’s team.

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

He 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 of the bad acts and crimes on the other side. A TOTAL WITCH HUNT LIKE NO OTHER IN AMERICAN HISTORY!”

In his tweets, Trump misstated Mueller’s background. A registered Republican, he was nominated to be FBI director in 2001 by President George W. Bush. In 2011, President Barack Obama gave his original 10-year term a two-year extension.

Mueller was tapped to be special counsel last year by Deputy Attorney General Rod J. Rosenstein, who started overseeing the Russia investigation after Sessions recused himself, citing his role in Trump’s 2016 presidential campaign.

White House officials have sought in recent days to highlight their continuing cooperation with Mueller’s team despite Trump’s opinion of the probe.

Speaking to reporters later Thursday, House Minority Leader Nancy Pelosi (D-Calif.) said she considered Trump’s tweets to be part of “an all-out campaign to obstruct the Mueller investigation.”

During an appearance Thursday morning on CNN, Rep. Jerrold Nadler (D-N.Y.) said he is concerned that Trump’s description of the “inner workings” of the Mueller investigation could signal that Whitaker is inappropriately sharing details about it with the president.

“Of course with this president, we don’t know. He may have simply made that up because he lies all the time,” said Nadler, who is in line to become chairman of the Judiciary Committee when Democrats take control of the House in January.

Nadler said it appears to him that Whitaker was appointed with the “express purpose of being a hatchet man to sabotage this investigation.”

More than two hours after his initial tweets Wednesday about the Mueller investigation, Trump returned to the subject later, accusing Mueller of protecting 2016 Democratic presidential nominee Hillary Clinton, several former FBI officials and “all of his friends on the other side.”

“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 wrote. “Why is he protecting Crooked Hillary, Comey, McCabe, Lisa Page & her lover, Peter S, and all of his friends on the other side?”

Mueller’s job is not one that requires Senate approval.

Trump did not spell out why he thinks Mueller is “highly conflicted.”

In the past, Trump and White House officials have alluded to an alleged dispute over fees when Mueller resigned in 2011 as a member of the Trump National Golf Club in Northern Virginia. A spokesman for Mueller, who was FBI director at the time, said there was no dispute when Mueller left the club.

In another tweet Wednesday, Trump repeated a previous assertion that the only collusion in 2016 was between Russia and Democrats, and he lashed out at social media companies, accusing them of favoring Democrats. “That’s the real Collusion!” Trump wrote.

Senate Majority Leader Mitch McConnell (R-Ky.) has been blocking a bipartisan effort to protect Mueller’s investigation through legislation, saying he has seen no evidence that the White House will shut it down.

The bill would give any fired special counsel the ability to swiftly challenge their termination before a panel of three federal judges.

Senate Minority Leader Charles E. Schumer (D-N.Y.) cited Trump’s Thursday tweets as he urged his colleagues to press foward with the bill.

“There is too much at stake for us to sit around and wait until the president crosses a line, creating a constitutional crisis we all abhor,” Schumer said in remarks on the Senate floor.

Referring to Trump’s tweets, Schumer said Trump had “for what seems like the millionth time .... wildly and baselessly ranted about the special counsel’s investigation.”

“It doesn’t matter to him that his claims have no basis,” Schumer said. “It doesn’t matter to him that his words may degrade faith in our independent law enforcement agencies and the rule of law. He proceeds only according to self-interest.”

On Wednesday, the Justice Department released a memorandum defending the legality of Trump’s appointment of Whitaker, rejecting criticism from some lawyers that the move violates the Constitution.

Since the announcement last week, some have charged that Whitaker, who served as the chief of staff to Sessions, is ineligible to serve as head of the Justice Department because he is not a Senate-confirmed official.

Speaking to reporters, Pelosi echoed that view, saying Whitaker’s appointment made “a mockery of our Constitution.”

On Tuesday, Maryland Attorney General Brian E. Frosh, a Democrat, asked a federal judge to block Whitaker’s appointment, arguing that Rosenstein should instead take on the role.

Devlin Barrett and Karoun Demirjian contributed to this report. .