But Trump's problems with McCabe may be just beginning.
Unleashed by his Friday night dismissal, the former FBI deputy director issued a furious rebuttal — and made clear he kept contemporaneous memos that support former FBI Director James B. Comey's claims that Trump pressed him to call off at least part of the Russia probe — accounts Trump has denied.
Brusque firings and sudden resignations have become a blood sport in the Trump era, with the president stoking the chaos with scornful tweets. Trump unceremoniously fired Secretary of State Rex Tillerson with a Twitter post Tuesday, and White House officials last week warned that national security advisor H.R. McMaster is on his way out.
But the seeming cruelty of McCabe's last-minute firing — barely 26 hours before he turned 50 and planned to take his pension for 21 years of service at the FBI — sparked special outrage among otherwise sober-minded national security and law enforcement veterans.
"When the full extent of your venality, moral turpitude, and political corruption becomes known, you will take your rightful place as a disgraced demagogue in the dustbin of history," John Brennan, who headed the CIA from 2013 to 2017, wrote in a tweet directed to Trump. "You may scapegoat Andy McCabe, but you will not destroy America … America will triumph over you."
The race to kick McCabe out before he could retire "violates any sense of decency and basic principles of fairness," said Michael R. Bromwich, McCabe's lawyer and a former Justice Department inspector general.
He said pressure from Trump and his allies had pushed Atty. Gen. Jeff Sessions to fire McCabe, and the disciplinary process was rushed in little more than a week — far more quickly than normal.
McCabe clearly is not going out quietly. Like Comey, he kept detailed notes of his three meetings with Trump, according to a person familiar with McCabe's actions, as well as his conversations with Comey before Trump fired him last May.
The McCabe memos could become crucial evidence in the Russia investigation led by special counsel Robert S. Mueller III. His team is seeking to determine whether Trump obstructed justice, a potential crime, by trying to pressure Comey and others to influence or block an ongoing FBI investigation.
The notes also could bolster McCabe's credibility about his interactions with Trump since Sessions sacked him on allegations of making false statements during an internal inquiry into whether he had authorized two FBI officials to brief a reporter about an unrelated investigation.
The existence of the McCabe memos was first reported by the Associated Press.
In his scathing rebuttal, McCabe portrayed himself as a victim of a partisan smear campaign led by Trump's tweets — and suggested that he has eyewitness evidence about whether Comey or Trump is telling the truth.
"Here is the reality: I am being singled out and treated this way because of the role I played, the actions I took, and the events I witnessed in the aftermath of the firing of James Comey," McCabe wrote.
He said Trump had sought to discredit him as part of "this administration's ongoing war on the FBI and the efforts of the special counsel investigation."
McCabe said an inquiry into his actions was fast-tracked at the Justice Department after he gave closed-door testimony to the House Intelligence Committee in December that backed Comey's account of his meetings with Trump.
But Trump launched a sweeping new attack Saturday, suggesting that his enemies were burrowed across the federal government. "There was tremendous leaking, lying and corruption at the highest levels of the FBI, Justice & State," he wrote on Twitter.
A Trump lawyer, John Dowd, called on Deputy Atty. Gen. Rod Rosenstein, who oversees Mueller's investigation, to "follow the brilliant and courageous example" of Sessions in firing McCabe and "bring an end to alleged Russia collusion investigation."
Dowd initially told the Daily Beast he was speaking for the president but later said he made the statement on his own.
Either way, it suggested a far more combative approach by Trump's legal team days after it was reported that Mueller had issued a subpoena in recent weeks seeking records from the Trump Organization, the umbrella group that holds the president's businesses.
Trump's lawyers previously insisted they were offering full cooperation with Mueller's team, highlighting their willingness to turn over documents and make White House officials available for interviews without subpoenas.
While Trump and his lawyers have consistently denied collusion with Moscow, they have occasionally struggled to speak with one voice on the Russia case. Dowd previously sparked controversy when he suggested Trump could not obstruct justice because the president is too powerful and controls the Justice Department.
Dowd also belatedly claimed to have written a Trump tweet that suggested the president knew his former national security advisor, Michael Flynn, had lied to FBI investigators when he fired Flynn in early 2017. The tweet had raised awkward questions for the White House of what Trump knew about the Russia case at the time.
McCabe first came into the public eye last year after the Justice Department inspector general began a wide-ranging inquiry into whether the FBI mishandled a 2016 investigation into Hillary Clinton's use of a private server for government emails while she was secretary of State, and a separate probe into the Clinton Foundation, a charity.
As FBI deputy director, McCabe supervised those investigations, which concluded without criminal charges. But he had authorized two FBI officials to talk to a Wall Street Journal reporter about the Clinton Foundation investigation, a potential violation of department rules because the investigation was still underway.
McCabe made false statements to the inspector general "under oath," Sessions said in a Justice Department statement late Friday announcing McCabe's dismissal.
In his statement, McCabe said he "answered questions truthfully and as accurately as I could amidst the chaos that surrounded me." He also said that as deputy director, he was "fully authorized" to share information with reporters.
McCabe's testimony to the House Intelligence Committee made him a lightning rod in the partisan squabble over the so-called Steele dossier, opposition research on Trump's dealings with Russia that was collected by a former British spy then working for a Washington firm hired by the Democrats.
In a declassified memo last month, Republicans on the committee wrote that McCabe had testified that the dossier was key to obtaining a surveillance warrant on a former member of Trump's campaign.
But McCabe said the Republican memo misrepresents his testimony.
Rep. Adam B. Schiff (D-Burbank), the committee's top Democrat, said in an interview Saturday that McCabe answered a "very awkward, convoluted question" about the dossier. He urged the Republican majority, which has concluded its inquiry, to release transcripts of McCabe's interviews.
Schiff said McCabe had confirmed Comey's claims about Trump to the committee, and said the president's tweets had left a "foul taint" on the firing.
Sen. Kamala Harris (D-Calif.) said Sessions should appear before the Senate Judiciary Committee to explain "whether this is an attempt to target, punish or silence those investigating Russia and the Trump campaign."
But McCabe's ouster drew praise from some Republicans. Rep. Bob Goodlatte (R-Va.), chairman of the House Judiciary Committee, said more investigations are needed to "root out the problems in the FBI."