President Donald Trump, who was defeated by Democratic challenger Joe Biden earlier this month, insists without evidence that widespread voter fraud cost him the election.

Mr Barr wrote to prosecutors yesterday to authorise them to “pursue substantial allegations of voting and vote tabulation irregularities prior to the certification of elections in your jurisdictions in certain cases”.

However, Richard Pilger, the prosecutor in charge of elections crimes, announced that he “must regretfully resign” from his position in light of the new policy, NBC News reports.

He said it represented a break from the previous rule that “overt investigative steps ordinarily should not be taken until the election in question has been concluded, its results certified, and all recounts and election contests concluded”.