WASHINGTON — Lawyers for Michael T. Flynn, the president’s first national security adviser, asked a federal judge on Friday to delay his sentencing in an apparent bid to relitigate the case in which he has twice admitted guilt.
The latest move by the defense lawyers could anger the federal judge who will sentence him, Emmet G. Sullivan, who might have lingering doubts about whether Mr. Flynn truly accepts responsibility for his crime of lying to the F.B.I. and whether he fulfilled his cooperation agreement with the government in one of the still-lingering cases brought by the special counsel, Robert S. Mueller III.
Judge Sullivan already rebuked Mr. Flynn for suggesting in earlier court papers that the F.B.I. had tricked him into lying when agents questioned him at the White House in January 2017 as part of the Russia investigation. The judge then delayed Mr. Flynn’s sentencing in December 2018 so he could testify for the government against a former business partner, Bijan Kian, to maximize the help that Mr. Flynn was providing to prosecutors.
But Mr. Flynn changed his story on the eve of Mr. Kian’s trial on charges of violating foreign lobbying laws. Mr. Flynn had previously admitted that he too lied on foreign lobbying disclosure forms submitted to the Justice Department but then, in an unusual turn of events, blamed his former lawyers for filing inaccurate forms without his knowledge.
Prosecutors declined to use Mr. Flynn as a witness in the trial of Mr. Kian, who was convicted in July, prompting questions about how Judge Sullivan would determine whether Mr. Flynn had fulfilled his obligations to help the government as part of his plea deal for a more lenient sentence.
Mr. Flynn’s change of course has heightened speculation that he could be making a bid for a pardon from the president. A former personal lawyer for Mr. Trump broached the prospect with a previous lawyer for Mr. Flynn two years ago as the special counsel was closing in on charging him, raising questions about whether the president’s lawyer was trying to influence Mr. Flynn’s decision to cooperate with the special counsel.
The government had previously recommended a punishment of probation without prison time for Mr. Flynn, but the judge could decide to sentence him to prison if he believes that Mr. Flynn lacked contrition and failed to live up to his obligations. Judge Sullivan had said he was disgusted that Mr. Flynn illegally lied to F.B.I. agents and did so in the White House.
“This is a very serious offense,” Judge Sullivan said at the December hearing. “A high-ranking senior official of the government making false statements to the Federal Bureau of Investigation while on the physical premises of the White House.”
In a joint filing submitted to the judge on Friday, Mr. Flynn’s new lawyers said he had fully cooperated with the government but argued that the case was not ready to be sentenced because they required more time to review all the information they received from his previous lawyers and asked for an additional 90 days before sentencing. Prosecutors said they were ready to schedule a sentencing sooner.
Mr. Flynn hired new lawyers in June, including Sidney Powell, who has repeatedly attacked the special counsel’s prosecutors in appearances on Fox News.
Ms. Powell told the judge that she also requires a security clearance and access to classified material related to Mr. Flynn’s conversations with the Russian ambassador, Sergey I. Kislyak, in the month after Mr. Trump’s election. The lies Mr. Flynn told to F.B.I. agents came in response to questions about whether he and Mr. Kislyak discussed sanctions that the departing Obama administration had just imposed on Russia.
“We must have access to that information to represent our client consistently with his constitutional rights and our ethical obligations,” Mr. Flynn’s lawyers wrote.
The classified transcripts of the calls make clear that the two men discussed sanctions at length and that Mr. Flynn was highly unlikely to have forgotten those details when questioned by the F.B.I., several former United States officials familiar with the documents have said. It was clear, the officials said, that sanctions were the only thing Mr. Flynn wanted to talk about with Mr. Kislyak.
Mr. Flynn’s lawyers also suggested in the filing that the government had exculpatory material, but it is not clear if they consider the transcripts to be that material.
In their terse response to Mr. Flynn’s defense lawyers, prosecutors said in the filing that Mr. Flynn’s cooperation was over and dismissed requests for more information.
Prosecutors added that they are “not aware of any issues that require the court’s resolution prior sentencing,” and “the government is not aware of any classified information that requires disclosures to the defendant or his counsel.”
Judge Sullivan scheduled a Sept. 10 hearing on the issues in the case.