By Steve Holland

WASHINGTON U.S. President Joe Biden turns 81 on Monday, a milestone likely to draw attention to his status as the oldest person to ever occupy the Oval Office, with opinion polls showing Americans worried he is too old for the post he is seeking reelection to.

Biden has addressed those who worry that he is too old for the rigors of the White House with humor and an attempt to convince voters that his age and experience over a half-century in public life is an asset in tackling America's problems.

"I know I'm 198 years old," Biden joked back in June.

If re-elected, Biden would be 86 by the end of his second term in office. Republican Ronald Reagan, who had the prior record as oldest U.S. president, ended his second four-year term at age 77 in 1989.

Trump, the frontrunner for the Republican nomination to challenge Biden in the 2024 election, is 77.

In a mid-September Reuters/Ipsos poll, voters expressed concern over Biden’s age and his fitness for office. Seventy-seven percent of respondents, including 65% of Democrats, said Biden is too old to be president, while just 39% said Biden was mentally sharp enough for the presidency.

By comparison, 56% of poll respondents said Trump is too old for the office, while 54% said he was mentally sharp enough to handle the challenges of the presidency.

(Reporting By Steve Holland; Editing by Bill Berkrot)