As he celebrates his 81st birthday on Monday, US President Joe Biden knows that his age is both a blessing and a curse in the run-up to the 2024 presidential election. During a speech to workers in the automotive industry, Biden joked about concerns about his physical fitness and mental sharpness, but he also acknowledged that his age is a major hurdle.

Biden is already the oldest president in American history, and if he wins a second term, he will be 86 years old when he leaves the White House. While his last systematic examination in February found him to be in good health, voters are increasingly skeptical about his ability to lead the country for another four years. A recent survey conducted by the Siena Institute and published by The New York Times revealed that 71% of voters believe that Biden is too old to be president. Only 39% think the same about former president Donald Trump, who at 77 is also not an “old chicken.”

However, there are concerns about Trump’s mental abilities as well, which have been increasingly questioned by critics. David Axelrod, the former chief strategist of Democrats, advised Biden to consider whether he is running for personal or national interest. Stuart Jay Olshansky, who studies longevity at the University of Illinois, said aging is not what it used to be and urged people to focus on what they can do rather than their age.

Despite these challenges, Biden plans to travel across America as he takes on increasing responsibilities as President. While his doctor describes him as “strong,” there’s no doubt that Biden’s appearance corresponds to his age. His gait is very stiff; his voice often weak and difficult to hear; and his speech was otherwise slurred. However, this doesn’t stop him from joking about being 800 years old or claiming that his age is a guarantee of wisdom on matters of American political life and turmoil in the world.