President Trump’s lawyers plan to cast former national security adviser Michael Flynn as a liar seeking to protect himself if he accuses the president or his senior aides of any wrongdoing, according to three people familiar with the strategy.

The approach would mark a sharp break from Trump’s previously sympathetic posture toward Flynn, whom he called a “wonderful man” when Flynn departed the White House in February. Earlier this month, the president did not rule out a possible pardon for Flynn, who is cooperating with special counsel Robert Mueller’s investigation into Russian interference in the 2016 election.

Attorneys for Trump and his top advisers have privately expressed confidence that Flynn does not have evidence that could implicate the president or his team. But since Flynn’s deal with prosecutors was made public earlier this month, the administration has been strategizing how to neutralize him in case the former national security adviser does make any claims.

Flynn is the most senior former Trump adviser known to be cooperating with Mueller’s team. The lenient terms of his plea suggest he has promised significant information to investigators, legal experts said.

Earlier this month, he pleaded guilty to one felony count of lying to the FBI, a charge that carries a maximum sentence of five years in prison. Prosecutors said they will recommend a sentence from zero to six months in prison as part of his cooperation deal. Flynn’s son, who served as his chief of staff, also faced the risk of criminal charges, according to people familiar with the plea negotiations, but was spared.

Trump’s legal team has seized on Flynn’s agreement with prosecutors as fodder for a possible defense, if necessary. In court filings, the retired lieutenant general admitted that he lied to the FBI about conversations he had with the Russian ambassador to the U.S. during the December 2016 transition.

“He’s said it himself: He’s a liar,” said one person helping craft the strategy who requested anonymity.

Robert Kelner, an attorney for Flynn, declined to comment. Ty Cobb, the White House attorney overseeing the response to the special counsel investigation, also declined.

Defense lawyers have said privately that Flynn will be unable to point to White House or campaign records turned over in the probe to bolster any claims of a criminal scheme. None of those records suggest a conspiracy by Trump or his inner circle to improperly work with Russians to defeat Democratic candidate Hillary Clinton, according to people who have reviewed the documents.

The private talks about assailing Flynn’s credibility come even as Trump has signaled that a pardon is not off the table.

“I don’t want to talk about pardons for Michael Flynn yet,” the president said Dec. 15. “We’ll see what happens. Let’s see. I can say this: When you look at what’s gone on with the FBI and with the Justice Department, people are very, very angry.”

Some of Flynn’s family members appear to be counting on Trump to act. On Tuesday, one of Flynn’s brothers tweeted a message urging the president to pardon his former adviser, responding to a tweet by Trump alleging bias in the FBI.

Exactly what Flynn might offer Mueller about what he saw inside the Trump operation remains a mystery. Barbara Van Gelder, a veteran white-collar defense lawyer and former prosecutor, noted that in the way the special counsel structured Flynn’s plea agreement, prosecutors avoided sharing the guts of their ongoing investigation.

“That is what I thought was the brilliance of the Flynn plea,” she said. “It said: ‘I’m giving just enough to have the judge sentence you within the guidelines, but not giving anything to anybody else.’ “