Washington DC - Prosecutors recommended Thursday that Donald Trump go on trial in January for allegedly conspiring to overturn the 2020 election, threatening the former president with a high-profile court case days before the Republican primary contest begins.

The Justice Department has accused the 77-year-old of plotting with aides to illegally pressure local and national government officials, as well as have party activists fraudulently certify bogus Trump victories in several states won by Joe Biden.

"The government's proposed trial date represents an appropriate balance of the defendant's right to prepare a defense and the public's strong interest in a speedy trial in the case," lead prosecutor Jack Smith said in a court filing asking for a January 2 start.

Trump, who is facing prosecution in multiple jurisdictions over allegations of criminal conduct before, during and after his presidency, quickly responded to the request with a furious post claiming "Election Interference."

"These Fake Indictments against me didn't come down from heaven, they came from the most corrupt President in the history of the United States, Crooked Joe Biden, in order to Rig & Steal another Election," he said.

Smith, a former war crimes prosecutor at The Hague, charged Trump last week with four felony counts: conspiracy to defraud the US, conspiracy to obstruct, and actual obstruction of, an official proceeding, and conspiracy against the right to vote.

The suggested start for what is expected to be one of the most sensational trials in US history would place it just before the anniversary of the January 6, 2021 insurrection, which prosecutors say was the culmination of the election plot.

Crucially, it would also come two weeks before the all-important Iowa caucus, the opening vote in the Republican primary season, where candidates can pick up crucial momentum.

Biden's attorney general, Merrick Garland, appointed Smith as a special counsel in the election conspiracy case, giving him sole charge of prosecuting decisions in a bid to avoid actual or apparent political influence.

The case is the most serious of four criminal probes that have yielded dozens of felony charges, including allegations that Trump covered up hush money payments to porn star Stormy Daniels in a bid to cheat campaign finance rules ahead of the 2020 election.

The government also accuses Trump of mishandling dozens of classified documents he took from the White House as he left office, including military plans and nuclear secrets, and plotting with his staff to hide them from investigators.

Trump's personal assistant Walt Nauta pleaded not guilty on Thursday to new federal charges brought over his alleged attempts to help Trump conceal documents that had been demanded in a grand jury subpoena.

The ex-president was also facing new charges – bringing the felony counts he faces in the case to 40 – but wasn't required to appear and signaled last week that he would be pleading not guilty.