WASHINGTON — When President Donald Trump fired James Comey in May, he said he was acting on the recommendation of Justice Department leaders who had faulted the FBI director for releasing “derogatory information” about Hillary Clinton at the conclusion of the email server investigation months earlier.

Yet with each tweet about the Clinton probe, Trump seems to be further undermining his administration’s stated rationale for a termination that’s now central to special counsel Robert Mueller’s Russia investigation.

The disconnect between Trump’s attacks on Comey’s handling of the email investigation and the criticism of Comey by his own Justice Department could muddy the explanation for exactly why Comey was fired, and may complicate efforts by the president’s legal team to present a coherent narrative as Mueller and his prosecutors examine whether the dismissal could support obstruction of justice allegations.

Trump has complained for months about the FBI’s decision not to pursue criminal charges against Clinton, his Democratic opponent in the 2016 presidential election, for her use of a personal email server. He has suggested the criminal investigation was rigged in her favor, claiming in one October tweet that Comey “totally protected” her. And in a Saturday tweet that appeared to suggest Clinton should have been prosecuted, Trump caustically referred to “33,000 illegally deleted emails.”

Yet those attacks are increasingly hard to square with a Justice Department memo that the White House held up as justification for firing Comey. That document, authored by Deputy Attorney General Rod Rosenstein, cited an unusual July 2016 news conference in which Comey described Clinton and her aides as “extremely careless” as well as Comey’s notification to Congress, days before the election, that the investigation was being revisited because of the sudden discovery of additional emails.

“From the beginning there’s always been serious doubt that the memo from the deputy attorney general was the actual reason the president fired the FBI director,” said Scott Fredericksen, a Washington criminal defense lawyer and former federal prosecutor.

Mueller’s team has been interested for months in the circumstances of Comey’s firing, with prosecutors obtaining an initial White House memo, drafted but never released, that purported to lay out a basis for Comey’s removal.

“The irony is most politicians would recognize that perpetuating silence post-firing would have been the most effective course,” said Jacob Frenkel, a Washington defense lawyer and former prosecutor.

In the event charges are brought or impeachment proceedings are begun, that kind of inconsistent messaging would present “not just entertaining fodder for cross-examination” but also material that could be used to challenge a witness’s credibility, Frenkel said.