President Donald Trump looks on after delivering an update on “Operation Warp Speed” in the Rose Garden of the White House in Washington, DC on November 13, 2020.Mandel Ngan | AFP | Getty ImagesPresident Donald Trump acknowledged publicly for the first time that President-elect Joe Biden won the election, more than seven days after media outlets including NBC News called the race for Biden.The president’s comments, made in a seemingly offhand post on social media, come as his campaign continues to challenge the results of the election in court and as his administration holds up formal transition processes.In subsequent tweets, Trump wrote that he would not concede.The ostensible acknowledgement of defeat came on Twitter, in response to a post by the Fox News show “Watters’ World” that suggested that Biden “didn’t earn” the presidency.”He won because the Election was Rigged,” Trump wrote, repeating an allegation that has been debunked by election officials around the country and his own Department of Homeland Security.Shortly after writing that Biden had won, though, Trump wrote in another post that he conceded “NOTHING” and claimed that “WE WILL WIN!””He only won in the eyes of the FAKE NEWS MEDIA,” Trump wrote.The flurry of tweets come as the president continues to argue without evidence that the election was rigged against him, energizing his base even in defeat.Thousands of his supporters gathered in Washington, D.C. on Saturday to protest the results. At least 20 people were arrested after pro-Trump groups clashed with counterprotesters.A White House official, when asked if Trump was admitting defeat, told NBC News: “It looks like it.” The official added that it may be the beginning of Trump conceding the presidential race.Biden’s chief of staff, Ronald Klain, said on NBC’s “Meet the Press” later on Sunday that he accepted the president’s post on Twitter “as a further confirmation of the reality that Joe Biden won the election.””If the president’s prepared to begin to recognize that reality, that’s positive,” Klain said. He added that “Donald Trump’s Twitter feed doesn’t make Joe Biden president or not president. The American people did that.”To date, more than 97% of the expected votes in the 2020 race have been tabulated. NBC News is projecting that Biden will snag 306 electoral votes, compared to Trump’s 232. It takes 270 electoral votes to win.Biden also leads Trump in the popular vote by a margin of more than 5 million votes, though the popular vote is not legally significant.The significance of the president’s acknowledgement was not immediately clear, particularly given his subsequent reversal.Trump’s reelection campaign is continuing to pursue litigation around the country seeking to slow the process of election certification in key states, or otherwise challenge election processes. Most of those efforts have been unsuccessful so far.Formal transition delayedHis administration has also not yet announced a formal acknowledgement of Biden’s win, which has resulted in a delay of millions of dollars in funding and the provision of other government resources for the transition effort.The administrator of the General Services Administration, Emily Murphy, must sign paperwork in order for the transition process to begin. The GSA did not return an email seeking comment. A Biden transition official told NBC News that they had not received any updates on the GSA process Sunday morning. The Biden team has continued to push on with the transition effort despite the Trump administration’s stonewalling. On Wednesday, Biden named Klain to be his chief of staff. Biden is expected to start filling out other roles in the coming weeks.The former vice president has projected confidence that the president’s efforts would not impede the peaceful transition of power.The Democrat’s team has repeatedly said in response to inquiries about the matter, “The United States government is perfectly capable of escorting trespassers out of the White House.”Biden called Trump’s refusal to concede an “embarrassment” on Tuesday but said that it would not slow the transition.”We have already started the transition; we are well under way,” he said at a press conference in Delaware.Republicans have been slow to acknowledge Biden’s victory, though there has been some movement in that direction in recent days. Senate Majority Leader Mitch McConnell, R-Ky., notably, has yet to refer to Biden as the president-elect.GOP Sens. Susan Collins of Maine, Mitt Romney of Utah, Lisa Murkowski of Alaska and Ben Sasse of Nebraska have congratulated Biden on his victory, as has the last Republican to hold the office, former President George W. Bush.Senior Republicans including Sen. Chuck Grassley of Iowa, Lindsey Graham of South Carolina, John Thune of South Dakota and James Lankford of Oklahoma have pressed for Biden to have access to classified intelligence briefings.