US President Donald Trump said Monday that Attorney General William Barr would step down on December 23.

Trump shared a letter on Twitter, in which Barr announced his resignation and said he updated the president on the review of voter fraud allegations in the 2020 presidential election. In the letter, Barr pledged the allegations "would continue to be pursued." He also praised Trump, saying he was "greatly honored that you called on me to serve your Administration."

Trump said Barr had done "an outstanding job," and would be "leaving just before Christmas to spend the holidays with his family."

In his tweet, Trump said Deputy Attorney General Jeff Rosen would take over the job until the inauguration of President-elect Joe Biden in late January.

Trump's defeat to Biden was confirmed by the Electoral College on Monday.

Trump-Barr relationship

Trump has previously expressed his frustration about Barr, who told The Associated Press earlier this month that the Justice Department had found no widespread election fraud that would change the outcome of November's election.

Democrats have accused Barr of acting like the president's personal attorney. "William Barr was willing to do the president's bidding on every front but one. Barr refused to play along with President Trump's nonsensical claims to have won the election," Jerrold Nadler, the Democratic chairman of the House of Representatives Judiciary Committee, said in a statement.

Barr began his second stint as attorney general in February 2019, after previously serving under George H.W. Bush.

He framed special counsel Robert Mueller's report on the investigation into suspected Russian interference in the 2016 US presidential election as favorable to Trump, even though Mueller said Trump could not be exonerated. Barr followed Trump's calls to "investigate the investigators" in conducting a criminal investigation into the origins of the FBI's probe into that same election.

Barr did not always side with the president, however. Earlier in 2020, he told American broadcaster ABC News that the president's tweets about Justice Department cases "make it impossible for me to do my job."