US Attorney-General William Barr will step down next week, he said on Monday, as the Electoral College confirmed President Donald Trump's loss to Democratic President-elect Joe Biden.
Barr, who had angered Trump by not supporting his incorrect claims that the Nov. 3 election result had been tainted by widespread fraud, said he would leave office on Dec. 23, a little less than a month before Biden is sworn in on Jan. 20.
Deputy Attorney-General Jeff Rosen will take over as acting attorney general after Barr's departure, Trump said.
Trump lashed out at Barr on Twitter over the weekend after the Wall Street Journal reported that Barr knew earlier this year about an investigation into Biden's son Hunter's taxes.
Trump retweeted a comment from radio host Todd Starnes saying Barr should be fired. "A big disappointment!" Trump said in his tweet.
Barr's fate in the waning days of the Trump administration had been in question since he said earlier this month that a Justice Department investigation had found no sign of major fraud in the election, contradicting Trump's claims.
Barr's resignation letter was released shortly after he briefed the president about the Justice Department's review into the Trump campaign's allegations of voter fraud. In it, Barr pledged the allegations "would continue to be pursued."
In the letter, Barr also praised what he called Trump's historic record, saying he had helped boost the economy, strengthen the military and curb illegal immigration.
"I am proud to have played a role in the many successes and unprecedented achievements you have delivered for the American people," Barr wrote.
Trump's legal team had accused Barr of failing to conduct a proper inquiry into the voter fraud claims.
Biden beat Trump by 306 to 232 votes in the state-by-state Electoral College that chooses the president, as well as by more than 7 million ballots in the popular vote.
Despite that, Trump has continued to claim loudly and without evidence that the election was marred by widespread fraud, allegations that have been repeatedly rejected by state and federal officials.
Trump has pursued a series of legal challenges in numerous states, but he has not managed to prevail in any of them.
Last week, the US Supreme Court rejected a long-shot lawsuit by Texas and backed by Trump and a number of other states seeking to throw out voting results in four states, dealing what is seen as the fatal blow in his quest to undo his election loss.
Trump has refused to concede the election and waited until late November before allowing the Biden transition team to access funds and other resources it needs to prepare for the peaceful transfer of power.