The attack on Mr. Mueller, a longtime Republican who was appointed F.B.I. director under a Republican president, George W. Bush, followed a statement by Mr. Trump’s personal lawyer published Saturday calling on the Justice Department to end the special counsel investigation. Together, the comments raised the question once again about whether the president might be seeking to lay the ground to try to fire Mr. Mueller.
The shift in tone comes just days after The New York Times reported that Mr. Mueller has subpoenaed records from the Trump Organization. Mr. Trump’s lawyers met with Mr. Mueller’s team last week and received more details about how the special counsel is approaching the investigation, including the scope of his interest in the Trump Organization specifically.
A president cannot directly fire a special counsel but instead can order his attorney general to do so, and even then has to give a cause like conflict of interest. Since Mr. Sessions, a former campaign adviser, has recused himself from the Russia investigation, to Mr. Trump’s continuing aggravation, the job would then fall to the deputy attorney general, Rod J. Rosenstein.
But Mr. Rosenstein has said as recently as last week that he sees no justification for firing Mr. Mueller, meaning that he would either have to change his mind or be removed himself. The third-ranking official at the Justice Department, Rachel Brand, decided last month to step down. The next official in line would be the solicitor general, Noel Francisco, a former White House and Justice Department lawyer under Mr. Bush.
Mr. Trump sought to have Mr. Mueller fired last June but backed down after his White House counsel, Donald F. McGahn II, threatened to quit. The president told The Times a month later that Mr. Mueller would be crossing a red line if he looked into his family’s finances beyond any relationship with Russia. The White House made no assertion last week that the subpoena to the Trump Organization crossed that red line, but Mr. Trump evidently has grown tired of the strategy of being respectful and deferential to the special counsel.
John Dowd, the president’s private lawyer, signaled the shift in approach in a statement given to The Daily Beast. “I pray that Acting Attorney General Rosenstein will follow the brilliant and courageous example of the F.B.I. Office of Professional Responsibility and Attorney General Jeff Sessions and bring an end to alleged Russia collusion investigation manufactured by McCabe’s boss James Comey based upon a fraudulent and corrupt dossier,” Mr. Dowd said.
When Mr. Mueller assembled his team, he surrounded himself with subject-matter experts and trusted former colleagues. As the team filled out, Republican allies of Mr. Trump noted that some high-profile members had previously donated money to Democratic political candidates. In particular, Republicans have seized on donations by Andrew Weissmann, who served as F.B.I. general counsel under Mr. Mueller, as an example of bias. Mr. Weissmann is a career prosecutor but, while in private law practice, he donated thousands of dollars toward President Barack Obama’s election effort.
In his Sunday morning Twitter blasts, Mr. Trump also renewed his attacks on Mr. Comey and Mr. McCabe, who like Mr. Mueller are also longtime Republicans.
“Wow, watch Comey lie under oath to Senator G when asked ‘have you ever been an anonymous source…or known someone else to be an anonymous source…?’” Mr. Trump wrote. “He said strongly “never, no.” He lied as shown clearly on @foxandfriends.”
He went on to dismiss reports that Mr. McCabe kept detailed memos of his time as deputy F.B.I. director under Mr. Trump, just as Mr. Comey did. Mr. McCabe left those memos with the F.B.I., which means that Mr. Mueller’s team has access to them.
“Spent very little time with Andrew McCabe, but he never took notes when he was with me,” Mr. Trump wrote. “I don’t believe he made memos except to help his own agenda, probably at a later date. Same with lying James Comey. Can we call them Fake Memos?”
Mr. Trump, who admitted last week that he made up a claim in a meeting with Canada’s prime minister and is considered honest by only a third of the American people in polls, stayed this weekend at the White House, where he evidently is spending time watching Fox News and stewing about the investigation.
The Republican majority on the House Intelligence Committee has concluded that there was no systematic collusion between Russia and Mr. Trump’s campaign and shut down its investigation, a decision that the Democrats on the panel objected to. The Senate Intelligence Committee is still actively investigating even as Mr. Mueller’s team is.
Mr. Mueller has established that Russia tried to interfere in the election to benefit Mr. Trump and indicted three Russian organizations and 13 Russian individuals in the effort, although the indictment included no allegation that the president’s campaign was involved. Mr. Trump’s administration last week sanctioned those organizations and individuals.
Mr. Trump fired Mr. Comey last May, at first attributing the decision to the F.B.I. director’s handling of the investigation into Hillary Clinton’s private email server but later telling an interviewer that he had the Russia investigation in mind when he made the decision. Mr. McCabe, who backed Mr. Comey, was fired on Friday after being accused of not being candid with an inspector general about whether he authorized department officials to talk with reporters about the Clinton inquiry in 2016.
The president has repeatedly argued that Mr. McCabe was tainted because his wife ran for the Virginia State Senate as a Democrat in 2015 and received hundreds of thousands of dollars in campaign contributions from an organization controlled by Terry McAuliffe, then the governor and a longtime friend of Bill and Hillary Clinton. Jill McCabe lost the race, and Mr. Trump reportedly told Mr. McCabe that she was a “loser.”
Mr. McCabe has characterized his firing as an attempt to impede Mr. Mueller’s investigation, which beyond collusion is also focused on whether the president has attempted to obstruct justice by firing Mr. Comey. “This is part of an effort to discredit me as a witness,” Mr. McCabe said on Friday.