Former national security adviser Michael Flynn exits a vehicle as he arrives for his sentencing hearing at U.S. District Court in Washington, U.S., December 18, 2018.

After months of delays, President Donald Trump's former national security advisor Michael Flynn could tell a federal judge on Friday that he has finished cooperating with the government and is ready to be sentenced.

But the retired Army lieutenant general's recent decision to replace his legal team with Sidney Powell, a fiery critic of special counsel Robert Mueller's probe of Russian election interference, struck some as a signal that Flynn could be angling for a pardon.

"It's a very delicate situation, and it's a strange choice to bring on a lawyer who regularly is lambasting the investigation that [Flynn] now is cooperating in," said former federal and New York state prosecutor Duncan Levin.

"This could be a straight-up Machiavellian ploy for a presidential pardon," Levin said. "But then again, it could also just be a big coincidence."

Flynn's lawyer and federal prosecutors face a Friday deadline to file a joint status report in Washington, D.C., federal court. In the last such report in March, Flynn asked Judge Emmet Sullivan for a 90-day extension because "there may be additional cooperation" for him to provide in a separate criminal case.

The Washington Post reported Thursday that Flynn was still planning to testify in that case in a federal court in Alexandria, Virginia.

Flynn pleaded guilty in December 2017 to a charge of lying to FBI agents about his conversations with a Russian diplomat in the weeks before Trump took office. Federal guidelines recommended a sentence of between zero and six months in jail — terms considered by some legal minds to be a sweetheart deal.

"I accept full responsibility for my actions," Flynn said in a statement at that time.

A year later, Flynn was set to be sentenced in court, where both Flynn's lawyers and prosecutors were prepared to argue that Flynn receive either no jail time at all — given his guilty plea and extensive cooperation with Mueller — or get the low end of the guideline range.

But his sentencing was delayed when Sullivan suggested to Flynn that he would have a better chance of avoiding any jail time by waiting to be sentenced until after he had finished cooperating.

Flynn also appeared more convinced to agree to a postponement after receiving a brutal tongue-lashing from Sullivan, who told him, "arguably, you sold your country out."

Sullivan's harshness surprised Powell, who recently replaced Robert Kelner and Stephen Anthony of Covington & Burling as Flynn's lawyer.

Mueller brought the original charges against Flynn, but the case is now being handled by prosecutors for the U.S. Attorney's Office for the District of Columbia, who took over after Mueller's team completed its broader probe earlier this year.

Powell is a former federal prosecutor who has described Mueller and other key figures related to the federal government's probes of Russian election interference — including former FBI Director James Comey and former FBI Deputy Director Andrew McCabe — as "creeps on a mission."

She also argued in a February 2018 op-ed for The Daily Caller that Flynn should "withdraw his guilty plea," in no small part because she viewed Sullivan as "the best person to confront the egregious government misconduct [of the Mueller probe] and to right the injustices that have arisen from it."

She had criticized the judge after Flynn's sentencing hearing last December.

Powell TWEET

But Powell told The Hill on Wednesday that Flynn would continue to cooperate with the government as part of his plea agreement. And legal experts told CNBC that the possibility of Flynn successfully withdrawing his guilty plea was extremely remote.

"The bottom line is, he got a great deal, and in all likelihood he's going to get probation," said defense attorney and former federal prosecutor David Weinstein.

Trump, in a tweet Wednesday, called Powell a "GREAT LAWYER" and wished them both luck.

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"It is so highly inappropriate for the target of an investigation to comment on the lawyer of a witness," Levin said.

But the tweet did suggest that Trump was still sympathetic to Flynn, and that he approved of Powell's hiring.

Weinstein said of a possible pardon: "I would like to think that's not what it was, but certainly that's something at the top of the list" of why Flynn retained Powell.

Whether he is pardoned or not, both Flynn's attorney and federal prosecutors are expected to argue that the retired three-star general receive a sentence at the low end of his guideline range.

"The only unknown is what the judge is going to do when they say, 'Okay, we're ready,'" Weinstein said.

WATCH: Judge postpones Michael Flynn's sentencing, says he 'sold his country out'