The next president will be the oldest ever to take office if either Joe Biden or Donald Trump wins the November 2024 US elections.

Biden’s age and public gaffes have been more closely watched and analysed, but his loud-mouthed Republican opponent’s errors are also getting more attention.

Trump has mixed up the Hungarian and Turkish leaders, boasted that he beat Barack Obama — not Hillary Clinton, his real opponent — in the 2016 election, and cautioned that the world might face a second, not a third, world war.

The former president’s rivals have been enjoying his blunders, eager to remind voters that Trump, the clear leader in Republican primary polls, is not that young either.

The campaign team of Ron DeSantis has been happily posting videos on social media of the 77-year-old real estate tycoon stuttering, fumbling with words, or looking feeble and sweaty. The Florida governor, a young 45, is ahead of Trump’s Republican rivals in most states’ opinion polls.

Meanwhile, Biden’s team is not displeased at having the chance, for once, to shift the focus on another old candidate — especially as the current president is celebrating his 81st birthday today.

The Trump camp has not taken kindly to such insults.

“Biden’s campaign must be as confused as their own candidate who is always in a state of confusion,” Trump spokesperson Steven Cheung told AFP.

In a harsh and biting statement, Cheung continued to ridicule Biden as “feeble and frail”, likely to fall and even “plainly dumb”.

Trump, at his campaign rallies, usually looks energetic, engaging for hours with a crowd of supporters.

But critics wonder if Trump’s frequent gaffes and the videos of him holding on to a rail on a ramp to avoid falling, or shaking as he holds a glass of water, are just signs of tiredness — or indications of physical or mental deterioration.

It is hard to tell from the outside, if Trump is as healthy as he appears to be during his campaign meetings.

Biden seems older than Trump, even though they are close in age, said political scientist Kyle Kondik.

The polls agree: Two-thirds of Americans think the current president is too old for a second term, while only half of those polled say the same about Trump, who is slightly younger.

Kondik said it is unclear how the two will fare once the campaign is in full swing. He added that Trump’s verbal errors are more easily forgiven than Biden’s, simply because Trump has done so many of them.

The Republican does not get the same attention over his physical state as his Democratic opponent does.

As US president, Biden — who often bikes with his Secret Service team — undergoes a comprehensive series of yearly medical exams, the outcomes of which are shared in detail with the press.

Biden’s most recent health report said he was “healthy (and) energetic,” but it also noted that a small growth had been taken out from his skin and that he had a colonoscopy in 2021.

But since Trump stepped down three years ago, hardly any information has been given about the health of the former president, who loves fast food and seems to exercise little to none except on the golf course.

The age of presidents was a lively topic of discussion during Ronald Reagan’s second term, in the 1980s, when some watchers wondered if he was showing signs of mental deterioration.

It was revealed that Reagan had Alzheimer’s disease, years after he left office at age 77.

In 1994, former president Jimmy Carter himself raised an alarm in an article in the Journal of the American Medical Association, alerting of the “risk” to the United States if a president had a “neurological disease” that lowered his ability for leadership.

The DeSantis campaign has been increasingly emphasising Trump’s age and mistakes.

“The president is not a role for an 80-year-old,” DeSantis said on Sunday on CNN.

Nikki Haley, a 51-year-old who is running for the Republican presidential nomination, has repeatedly demanded mandatory mental ability tests for politicians over 75.

But nothing like that seems likely in the near future.