The tweet culminated a day in which Mr. Trump worked to take back an apparent acknowledgement that Joe Biden had won the White House.

Mr. Trump’s earlier comments had given some critics and supporters hope that the White House was ready to begin working on a transition with Mr. Biden’s team. Not so fast, Mr. Trump would soon make clear.

Mr. Trump, without using Mr. Biden’s name but referring to him, said “He won” as part of a tweet that made baseless claims about a “rigged” election. But as the president saw that his comments were being interpreted as his first public acknowledgment of a Biden victory, Mr. Trump quickly reversed course.”He only won in the eyes of the FAKE NEWS MEDIA,” Mr. Trump subsequently tweeted. “I concede NOTHING! We have a long way to go. This was a RIGGED ELECTION!”

There was no widespread fraud in the 2020 election. In fact, election officials from both political parties stated publicly that the election went well, and international observers confirmed there were no serious irregularities. Mr. Trump’s campaign has tried to mount legal challenges across the country, but many of the lawsuits have been thrown out and none has included any evidence that the outcome might be reversed.

Mr. Biden defeated Mr. Trump by winning back a trio of battleground states: Michigan, Wisconsin and Pennsylvania, and topped the 270 electoral vote threshold to clinch the presidency. Mr. Biden so far has 78.8 million votes, the most ever by a winning candidate, to Mr. Trump’s 73.1 million, according to an Associated Press tally.