The Trump administration is making plans to attack the credibility of Michael Flynn if he testifies against the president or his top aides, the Washington Post reported Wednesday. The plan, which the Post learned of from three sources, would mark a shift in the president’s tone toward his former national security adviser, whom Trump has spoken of warmly even after he was fired from the White House and pleaded guilty to lying to the FBI.

The plan, which can be considered a somewhat standard legal maneuver, feeds further into speculation over what Flynn knows, as well as over what the Trump team thinks Flynn knows. According to the Post, Trump’s attorneys and advisors have been confident Flynn has no damaging evidence related to the White House team. But Flynn’s lenient plea deal has led some experts to believe he has promised information of some importance to the Mueller investigation into Russian interference with the election.

The plan to undermine Flynn’s credibility involves casting him as a liar—a task that might be made easier given lying is exactly what he’s pleaded guilty to—and as someone looking out for his own self-interest, and for the protection of his son. Flynn is expected to receive a short sentence for lying to the FBI about conversations he had with a Russian ambassador during the transition period after the 2016 election, and his son has avoided criminal charges altogether.

On Tuesday, Michael Flynn’s brother tweeted at the president that it was “[a]bout time you pardoned General Flynn who has taken the biggest fall for all of you given the illegitimacy of this confessed crime in the wake of all this corruption.” He then deleted the tweet and replaced it with a more restrained one.

Mr. President, I personally believe that a pardon is due to General Flynn, given the apparent and obvious illegitimacy of the manner in which the so called "crimes"he plead guilty to were extracted from him. I ask for quick action on this. Thank you and keep up the good work! — Joseph J. Flynn (@JosephJFlynn1) December 27, 2017

Earlier in December, Trump didn’t rule out a possible pardon for Flynn, instead choosing to criticize the FBI and the Justice Department.