"Andy's in a difficult position now . . . because of the hyperpartisan political environment,'' said John Pistole, who held the FBI's No. 2 job for six years under former director Robert Mueller. Mueller now serves as special counsel, running the investigation into whether any Trump associates conspired with Russian agents to interfere with the 2016 election.
Pistole said McCabe "is weathering the storm".
"It's disappointing," he added, "to see how the criticism of the FBI is being used to try to undermine the credibility of the Mueller investigation. I think they've figured out they can't undermine Bob's integrity, so they're just going to go after whoever they can dig up any dirt on.''
Within the agency, there is praise - but also some criticism - for how McCabe has handled his role. Still, he has become a lightning rod in the political storms now buffeting the bureau. Conservatives have called for heads to roll at the FBI, and McCabe is atop many of their lists. But current and former FBI officials said it would be dangerous to appease those demands.
"It would send a terrible message to move him now, but it's also a terrible situation he's in,'' said one law enforcement official.
Last week, the FBI's top lawyer, James Baker, told colleagues he was being reassigned, according to people familiar with the matter.
McCabe won't become eligible for his full pension until early March. People close to him say he plans to retire as soon as he hits that mark. "He's got about 90 days, and some of that will be holiday time. He can make it,'' said one.
A spokesman for McCabe declined to comment, as did an FBI spokesman.
Word of McCabe's plans drew a response Saturday from Trump, who in a Twitter post characterised the move as "racing the clock to retire with full benefits".
The pressure on McCabe has only intensified, though. He got an eight-hour grilling from the House Intelligence Committee on Wednesday and returned to Congress on Friday to face more than nine hours of questions from the House Judiciary and Oversight committees.
Other senior FBI officials, including those who worked closely with McCabe and Comey, are expected to face similar questioning from Congress next year.
Republicans, in particular, are focusing on the FBI's relationship with the author of a dossier containing allegations against Trump. The bureau offered to pay the author of that document after the election to keep pursuing leads and information, but the agreement was never finalised, the Washington Post reported earlier this year.
The chairman of the Senate Judiciary Committee, Senator Charles Grassley, (R), has called for McCabe's ouster, saying he "ought to go for reasons of being involved in some of the things that took place in the previous administration. We want to make sure that there's not undue political influence within the FBI - the [Justice] Department and the FBI."
Democrats emerging from Friday's questioning of McCabe urged him to resist Republicans' calls to step down, saying the GOP's new focus on McCabe smells of political opportunism.
"Mr McCabe should in no way be fired by biased political commentary," said Congresswoman Sheila Jackson Lee, (D).
Trump and his supporters have made clear they want McCabe gone, but as a civil service employee, he can't be fired outright without some clear finding of major wrongdoing.
Christopher Wray became the FBI's new director in August, and typically when a new director arrives, he appoints a new deputy to help run the agency. When Comey became director in 2013, for example, he got a new deputy after about two months.
But within the FBI, even reassigning McCabe is viewed by many as a bad idea. It would be seen as caving to political demands and might provoke calls for additional housecleaning, according to current and former law enforcement officials.
McCabe rose quickly through the FBI's senior ranks, only to find himself, beginning last year, the subject of intense partisan fighting about his conduct.
Republicans attacked him after reports that his wife, a Democratic candidate for a Virginia Senate seat in 2015, had received hundreds of thousands of dollars in campaign donations from the political action committee led by a close ally of the Clintons. He had also been part of discussions with Justice Department officials that critics said prevented FBI agents from more aggressively pursuing their investigation of the Clinton Foundation. Agents were trying to determine whether donations to the foundation were made with an expectation of government favors from Clinton or her allies.
After reports about those issues surfaced in October 2016, then-candidate Trump singled out McCabe for criticism, and congressional Republicans demanded detailed answers from the FBI about his role in the Clinton probes - questions they insist remain unanswered.
In a separate Twitter post today, Trump expressed his incredulity once more, asking how "How can FBI Deputy Director Andrew McCabe, the man in charge, along with leakin' James Comey, of the Phony Hillary Clinton investigation (including her 33,000 illegally deleted emails) be given US$700,000 for wife's campaign by Clinton Puppets during investigation?"
McCabe's role is being examined by the Justice Department's inspector general, who has said a report on how the Clinton probe was handled should be finished by the next northern spring.
