US President Joe Biden is taking calls to step aside as the Democratic presidential candidate seriouslyand multiple Democratic officials think an exit is a matter of time, according to sources familiar with the matter.

"His soul searching is actually happening, I know that for a fact," said one of the sources, who requested anonymity. "He's thinking about this very seriously."

Biden, 81, has faced increasing pressure from heavyweights in his party to cede his position at the top of the ticket after a shoddy debate performance against former President Donald Trump, the Republican nominee, raised fears about his age and ability to win in November.

The president has pushed back defiantly against those calls, arguing that he has won millions of votes in primary races over the last several months and is Democratic voters' choice. As recently as Wednesday, he vowed "I am all in" the 2024 race.

Another of the sources, a Democratic congressional aide, said the writing appeared to be on the wall for the president after lawmakers including Senate Majority Leader Chuck Schumer reportedly urged him to drop out of the race.

"It feels like it's a matter of ... when, not if," the aide said.

Biden is convalescing from COVID-19 at his home in Rehoboth Beach, Delaware. He had no public events on Thursday after concluding a trip to the political swing state of Nevada on Wednesday.

Biden's campaign is focusing on three out of seven battleground states after the debate, a narrow path to victory, but it has rejected suggestions that he is ready to step aside.

"He is not wavering on anything. The president has made his decision," deputy campaign manager Quentin Fulks said in Milwaukee, where the Republican convention is taking place. "Joe Biden has said he is running for president of the United States. Our campaign is moving forward."

Another source, a Biden campaign official, said the opposite. "Yes, it's over. Just a matter of time."

  - Reuters