US attorney general William Barr said on Tuesday that the justice department has not uncovered voting fraud at a scale that could have affected the results of the presidential election, reaffirming Joe Biden’s win despite President Donald Trump’s groundless claims that he was defrauded.

Mr Barr’s comments, in an interview with The Associated Press, were a prominent repudiation of Mr Trump’s baseless assertions and came days after the president implied that the justice department and the FBI may have played a role in an election fraud.

“To date, we have not seen fraud on a scale that could have affected a different outcome in the election,” Mr Barr said.

Mr Barr’s comments came as another Trump ally signalled, he was ready to move on after a surreal month of lawsuits, conspiracy theories and denials by the president of a loss that has proved durable and decisive.

Republic senator for Kentucky, and majority leader, Mitch McConnell, who has refused to recognise Mr Trump’s election loss, on Tuesday moved closer to overtly accepting the reality that Mr Biden would be in the White House next year, while discussing the prospects for more pandemic stimulus in 2021.

“After the first of the year, there is likely to be a discussion about some additional package of some size next year, depending upon what the new administration wants to pursue,” Mr McConnell said at a news conference.

Taken together, Mr Barr’s direct declaration and Mr McConnell’s indirect reference to Mr Biden’s new administration represent a major, if not unexpected, blow to the president’s post-election effort to change the results from two men whom he has often relied on for political cover.

Moments after Mr Barr’s comments were made public, Rudy Giuliani, Mr Trump’s lawyer, emailed a statement on campaign letterhead, claiming – again without evidence – that he had found “ample” proof of national voter fraud sufficient to swing the election to Mr Biden.

“With the greatest respect to the attorney general, his opinion appears to be without any knowledge or investigation of the substantial irregularities and evidence of systemic fraud,” Mr Giuliani wrote late on Tuesday.

Mr Barr was seen entering the White House grounds on Tuesday afternoon. A department spokesman said he was there for previously scheduled appointments that did not include a meeting with the president.

Amid the fallout from Mr Barr’s statements about the election, the justice department also announced that he had given extra protection to the federal prosecutor examining the origins of the investigation into links between Mr Trump’s campaign and Russia.

Mr Barr appointed the prosecutor, John Durham, as a special counsel, a move that makes it more difficult for the Biden administration to fire him without providing evidence of misconduct.

Mr Durham has been conducting the investigation for a year and a half, and Mr Trump and his allies had been banking on him uncovering wrongdoing by Obama-era FBI officials to help the president’s political fortunes in the lead-up to last month’s election.

But Mr Durham has charged only one person, an FBI lawyer who pleaded guilty to doctoring an email.