Washington DC - Joe Biden's biographer has said it "wouldn’t be a total shock" if the president drops out of the 2024 race for the White House.

Franklin Foer, author of The Last Politician: Inside Joe Biden’s White House and the Struggle for America’s Future, told NBC's Meet the Press on Sunday that "it doesn’t take Bob Woodward to understand that Joe Biden is old."

"I'm not a gerontologist, and I can't predict how the next couple years will age Joe Biden," the 80-year-old president's biographer continued.

When asked if he would be surprised if Biden announced he would not seek a second term, Foer responded, "I would say it would be a surprise to me, but it wouldn't be a total surprise to me."

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"It wouldn't be a total shock," he added.

"When [Biden] talks about his life, he uses this word 'fate' constantly. Joe Biden is a very religious guy, and fate is a word loaded with religious meaning," Foer went on to explain. "When I hear that, to me, it's the ellipses in the sentence when he's talking about his own future that I account for in thinking about his calculus."

Biden announced his campaign for reelection in April and has not indicated he plans to back out of the race, despite widespread concerns about his age and fitness for the role.