WASHINGTON (AFP) -- US President Donald Trump faced fresh accusations of abuse of power Tuesday after the Justice Department moved to override its own prosecutors who are seeking a stiff sentence of seven to nine years for Republican political operative Roger Stone.

In new turmoil for the administration, the four prosecutors who tried the Stone case resigned as the Justice Department suggested a new sentence of less than half of what was originally recommended.

The proposed reduction appeared to be a response to Trump's late-night tweet attacking the recommended sentence.

Stone, who was convicted in November of lying to Congress and witness tampering, is a longtime Trump cohort.

"This is a horrible and very unfair situation. The real crimes were on the other side, as nothing happens to them. Cannot allow this miscarriage of justice!" Trump tweeted.

Later Trump denied speaking to the Justice Department about the case, while again condemning the sentence proposal.

"I thought the recommendation was ridiculous," he told reporters.

Senior House Democrat Adam Schiff said that Trump's apparent interference threatened the rule of law.

"It would be a blatant abuse of power if President Trump has in fact intervened to reverse the recommendations of career prosecutors at the Department of Justice," Schiff, who led the impeachment investigation of Trump, said in a statement.

"Doing so would send an unmistakable message that President Trump will protect those who lie to Congress to cover up his own misconduct, and that the Attorney General will join him in that effort."

'Extreme and excessive'

Stone, who has advised Trump on politics for decades and consulted on his successful 2016 presidential campaign, was arrested in January 2019 at his home in Florida on charges brought by then-special counsel Robert Mueller as part of the Russia meddling investigation.

He was charged in connection with his 2017 testimony to lawmakers on the House Intelligence Committee -- which Schiff leads -- investigating Kremlin efforts to damage Trump's election rival Hillary Clinton.

Stone was accused of lying about acting as an intermediary between the Trump campaign and WikiLeaks, which released hacked documents that embarrassed Clinton during the campaign.

"The evidence in this case will show that Roger Stone lied to the House Intelligence Committee because the truth looked bad -- the truth looked bad for the Trump campaign and the truth looked bad for Donald Trump," prosecutor Aaron Zelinsky told the jury.

Stone's conviction on all seven counts in November made him the sixth person tied to Trump to be convicted on charges brought by Mueller.

Prosecutors called for a sentence of 87 to 108 months on Monday, saying Stone threatened a witness in the case and implicitly threatened the judge by posting a picture of her on Instagram with what appeared to be a gunsight's crosshairs.

He also repeatedly lied to the court and disobeyed a gag order, prosecutors said.

In the wake of Trump's late-night tweet, an unnamed senior Justice Department official criticized the sentence to reporters early Tuesday.

"The department finds the recommendation extreme and excessive and disproportionate to Stone's offenses," the official said.

Later, a new court filing from prosecutors suggested 37 to 46 months might be more appropriate, calling it "more in line with the typical sentences imposed in obstruction cases."

'Mueller people'

The resignation of the four government attorneys from the case due to the extraordinary intervention sparked fresh turmoil in the Justice Department, already under pressure amid accusations that Attorney General Bill Barr has been too willing to protect Trump and do his bidding.

Two of the prosecutors served on the Mueller team investigating possible collusion between the Russians and the Trump campaign in 2016, and stayed with the Stone case after the investigation wound up nearly a year ago.

Trump had labelled that investigation, which generated charges against 34 individuals but none on the president, a politicized "witch hunt."

"These are the same Mueller people that put everybody through hell. I think it's a disgrace," Trump said late Tuesday.

But Democrats called for a probe into alleged Trump interference.

"Dictatorships, not democracies, give judicial preference to the president's friends & lackeys. This highly unusual move by the Justice Department should be investigated immediately," said Senator Richard Blumenthal, a member of the Senate Judiciary Committee which oversees the Justice Department. (AFP)