US President Joe Biden turns 81 on Monday, an event likely to draw attention to his status as the oldest person ever to hold the Oval Office, as polls show Americans worry he is too old for the job he is running to be re-elected in 2024, according to Reuters.

Biden humorously addressed those who worry that he is too old for the rigors of the White House, trying to convince voters that his age and more than half a century of experience in public life are an advantage in solving America’s problems.

“I know I’m 198 years old,” Biden joked in June.

If re-elected, Biden will be 86 years old at the end of his second term. Formerly the oldest US president, Republican Ronald Reagan completed his second four-year term in 1989 at the age of 77.

Donald Trump, 77, is the front-runner for the Republican nomination to challenge Biden in 2024, although neither has been officially nominated by his party.

In a Reuters/Ipsos poll in mid-September, voters expressed concern about Biden’s age and fitness for office.

77 percent of respondents, including 65 percent of Democrats, said Biden is too old to be president, while only 39 percent said the current White House leader is mentally sane for the presidency.

By comparison, 56 percent of those polled said Trump was too old for the job, while 54 percent said he was smart enough to handle the challenges of the presidency.

Americans who want to vote for Democratic President Joe Biden in 2024 say they are more motivated to prevent Donald Trump from returning to the Oval Office than to support the incumbent for another term, a new poll out last week found.

Many Americans, Reuters notes, are fed up with both Biden and Trump. A November poll showed strong support for independent candidate Robert F. Kennedy Jr., scion of a prominent political family and noted anti-vaccination campaigner.

In a hypothetical race between the three, 30% of respondents chose Biden, 32% Trump and 20% Kennedy.