Former White House National Security Advisor Michael Flynn leaves the Prettyman Federal Courthouse following a sentencing hearing in U.S. District Court December 18, 2018 in Washington, DC.

A federal judge on Monday delayed — once again — the sentencing of President Donald Trump's former national security advisor, Michael Flynn.

Flynn had been scheduled to be sentenced on Feb. 27 for lying to FBI agents about his contacts with former Russian ambassador Sergey Kislyak during the weeks between the 2016 presidential election and Trump's inauguration.

Judge Emmet Sullivan canceled that sentencing in his order Monday in U.S. District Court in Washington, D.C. Sullivan did not immediately set a new sentencing date.

On Sunday, prosecutors asked Sullivan to give them more time to reply to Flynn's pending bid to withdraw his guilty plea.

Prosecutors also asked the judge to confirm that Flynn had waived his attorney-client privilege with his prior defense team when he accused them of giving him "ineffective" legal representation.

"It is well-settled that a defendant waives his attorney-client privilege by filing a motion to vacate a conviction based on ineffective assistance of counsel," the prosecutors wrote.

If Sullivan approves that request, then prosecutors could ask Flynn's former attorneys for testimony to help them fight Flynn's withdrawal effort.

Sullivan ordered the prosecutors to file a status report on Feb. 20 evaluating Flynn's claim that his old lawyers had been ineffective. The judge also ordered both parties to hash out the terms of a proposal to waive Flynn's attorney-client privilege with his past legal team by Feb. 24.

It is far from clear that Flynn's new attorney would agree to any waiver of confidentiality with his former lawyers. On Sunday, that current lawyer, Sidney Powell, said, "It is imperative that Mr. Flynn have time to brief the issues raised by the government's new motion regarding the attorney-client privilege."

If no agreement can be reached, Sullivan ordered that Flynn must file an opposing brief by Feb. 24, and the prosecutors must submit their reply no more than a week later.

Flynn was originally set to be sentenced in December 2018, a year after he pleaded guilty as part of then-special counsel Robert Mueller's Russia probe.

That sentencing hearing was aborted after Sullivan implied that Flynn might be sentenced to jail, as opposed to mere probation. The delay in sentencing gave Flynn more time to complete agreed-to cooperation with Mueller's team, which Sullivan had suggested could weigh in his favor when he was ultimately sentenced.

Months later, Flynn dropped his team from D.C.-based law firm Covington & Burling, and hired Powell, an attorney who has been deeply critical of Mueller generally and the prosecution of Flynn specifically.

Powell for months in legal filings laid the groundwork for Flynn's formal request to withdraw his guilty plea.

Legal observers say Flynn faces long odds in getting Sullivan to allow him to retract his plea.