WASHINGTON (BLOOMBERG) - Roger Stone's sentencing for lying to Congress and witness tampering will proceed as planned on Thursday (Feb 20) despite his last-ditch request for a delay.

The Justice Department was also preparing to weigh in against Stone's request for a new trial, a department official said during a hearing on Tuesday with the judge overseeing the case, even after President Donald Trump seemed to push for one in a series of tweets that also took aim at the trial judge personally.

Trump has backed his longtime friend's claim that the jury foreman was biased against him.

The volleys on the eve of Stone's sentencing injected even more politics into the case.

Attorney-General William Barr has come under intense criticism since he overruled front-line prosecutors last week to reduce the recommended time that Stone should receive.

Stone's sentencing has already been delayed once, and he can still appeal even after his sentence is handed down, US District Judge Amy Berman Jackson said at the hearing in Washington.

Stone had asked for a delay of a few weeks while the court considers his request for a new trial.

Another delay "would not be a prudent thing to do under all the circumstances," Jackson said.

"I'm willing to make sure there are no consequences that flow from the announcement of the sentence at the sentencing hearing."

The prosecutors who led the case recommended Stone gets seven to nine years behind bars, but that was overruled by senior Justice Department officials after Trump criticised their suggestions as too harsh.

In another case that grew out of the Mueller probe, lawyers for former national security adviser Michael Flynn on Tuesday argued again that "egregious government misconduct" in the Russia investigation warrants dismissing Flynn's prosecution for lying to FBI agents about his contacts with Russia's ambassador.

Flynn's latest attempt to avoid sentencing comes less than a week after Barr ordered a review of the prosecution - yet another intervention in a politically sensitive case tied to Trump.

The president also weighed in on Flynn's case several times, including on Twitter in October when he called the prosecution a "disgrace".

In a filing in Washington, Flynn again cited the findings in an internal Justice Department report that criticised the FBI's efforts to obtain secret foreign intelligence warrants on then-Trump campaign adviser Carter Page at the start of the Russia investigation.

Flynn argued in the filing that one of the two FBI agents who interviewed him in January 2017 had broken "all protocols" because the agent surreptitiously participated in a presidential briefing the previous August to observe Flynn.

"The FBI assigned him specifically to collect information from and about Mr Flynn to give the FBI further advantage and insights in the agents' plan to interview Mr Flynn in the White House if Trump won the election," Flynn's lawyers said.

The government said last week that the Justice Department report's findings do not relate to Flynn's crimes.

A former army general, Flynn pleaded guilty in December 2017 but is now seeking to withdraw his plea before sentencing.