WASHINGTON - A US judge on Friday set aside pending deadlines in President-elect Donald Trump's 2020 election subversion case after federal prosecutors said they were grappling with the "unprecedented circumstance" of his impending return to the White House.

US District Judge Tanya Chutkan in Washington approved a request from Special Counsel Jack Smith, who is prosecuting the criminal case, to set aside the deadlines, according to a court order, while they weigh its future.

Prosecutors wrote the delay was necessary "to afford the Government time to assess this unprecedented circumstance and determine the appropriate course going forward consistent with Department of Justice policy."

READ MORE: Trump's impending return to White House brings criminal cases to a halt

Under a Justice Department policy dating back to the 1970s, a sitting president cannot be subject to criminal prosecution.

A source familiar with the matter told Reuters on Wednesday that the Justice Department was discussing how to wind down the case as Trump prepares to again assume the presidency.

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Trump pleaded not guilty last year to four criminal charges accusing the Republican of conspiring to obstruct the collection and certification of votes following his 2020 defeat to Democrat Joe Biden. The effort by Trump and his allies to reverse Biden's victory culminated in the deadly Jan 6, 2021, attack on the US Capitol following a fiery speech by the then-president near the White house.

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In Tuesday's election, Trump defeated Democratic Vice-President Kamala Harris, a victory all but certain to end two federal cases against him.

Trump's lawyers had been due to respond by Nov 21 to Smith's argument that the case can proceed after a US Supreme Court ruling giving former presidents broad immunity from prosecution over official actions taken while in office.

Smith said prosecutors would inform the judge by Dec 2 how they propose to move forward.