Former national security adviser Michael Flynn is expected to plead guilty Dec. 1 for lying to the FBI about his contacts with Russia.
The charges are part of special counsel Robert Mueller's investigation into possible Russian collusion during the 2016 presidential election, according to CNN.
Flynn is expected to plead guilty for "willfully and knowingly" making "false, fictitious and fraudulent statements" to the FBI about conversations with the Russian ambassador.
"Poor judgment," said a White House source who advises top officials on strategy. "But this was expected. Trump fired him for lying to [Vice President Mike Pence]. Of course, he lied to the FBI, too."
The former national security officer held his position for less than a month, resigning after he misled Pence and then-chief of staff Reince Priebus about his conversations with the Russian ambassador concerning U.S. sanctions against Russia.
FBI officials eavesdropped on the conversation as part of the investigation into Russian activities in the U.S. Flynn spoke to then-Russian ambassador to the U.S. Sergey Kislyak in December 2016, on the day former President Barack Obama issued new sanctions against Russia and expelled 35 diplomats from the country.
Flynn later resigned after the Department of Justice warned the White House that he could be susceptible to blackmail by the Russians.
According to the charging documents, Flynn lied to the FBI when he told investigators that he did not ask Kislyak "to refrain from escalating the situation in response to sanctions that the United States had imposed against Russia that same day; and Flynn did not recall the Russian ambassador subsequently telling him that Russia had chosen to moderate its response to those sanctions as a result of his request."
Flynn also falsely claimed to have not asked Kislyak to delay the vote on an upcoming United Nations Security Council resolution on Israeli settlements.
Previously, Flynn said that claims of his ties to Russia were "unfounded allegations, outrageous claims of treason, and vicious innuendo directed against him."
But the expected plea deal could indicate that he is cooperating with the federal investigators, giving them a behind-the-scenes look at White House proceedings.
The day after Flynn's resignation, then-FBI Director James Comey said President Donald Trump pressured him into dropping his criminal investigation, saying that Flynn was "a good guy," according to USA Today.
"I hope you can let this go," Trump allegedly told Comey.
Investigators are also looking into Trump's decision to fire Comey.