Though the first 2024 presidential primary contests are still months away, former President Donald Trump continues to comfortably lead the Republican field for the nomination. And no major challengers have posed a threat to President Joe Biden on the Democratic side.

Even though polling has shown a distaste for a 2020 rematch, next year’s race for the White House may be nearly identical to the last one.

While the two men could not be more opposed from a policy standpoint, they do have one thing in common: They’re both facing questions about fitness and age if voters were to give them a second term in the White House.

When he took office in 2017, Trump, then 70, was the oldest newly elected president. Four years later, Biden became the oldest president ever at 78.

As voters head to the voting booth next year, they too will be faced with a question: Should age matter when picking the president?

Biden uses humor to address his age; Trump attacks him on it

In an effort to assuage concerns about his age, Biden, 80, has attempted to embrace the topic with humor.

“I’ve been doing this a long time. I know I don’t look that old, I know,” Biden said to laughter at a gun safety summit in June. “I’m a little under 103.”

“I know I’m 198 years old,” Biden joked at an event in Tampa in February.

“You say I’m ancient? I say I’m wise,” Biden cracked at the White House Correspondents Dinner in April.

The Democratic president, who would be 86 at the end of his second term, is trying to own the issue of his advanced age with humor. He also makes optimism about the future a feature of his campaign speeches, despite adding that he’s “at the end of my career, not the beginning.”

It's not unlike how Ronald Reagan, who was 73 during his 1984 re-election campaign and was the oldest president at the end of his tenure at 77, handled questions about his age during the election. 

"I will not make age an issue of this campaign," Reagan said at a pivotal debate in October of 1984, joking at opponent Walter Mondale's expense: "I am not going to exploit, for political purposes, my opponent's youth and inexperience."

"We have seen Biden take a page from that playbook," said Lindsay Chervinsky, a presidential historian and author of "The Cabinet: George Washington and the Creation of an American Institution, adding: "He sometimes makes jokes about, his friend, Jimmy Madison, and the people he's known 200 years ago. So clearly, it was something that worked well, and I think Biden is hoping it will work well again."

But questions about age often arise after the occasionally gaff-prone Biden misspeaks, or after physical issues manifest – like when the president tripped over a sandbag on stage at the U.S. Air Force Academy graduation ceremony last month.

Trump, 77, faced his fair share of questions about his fitness to serve during his single White House term – like when the Republican president gingerly walked down a ramp at the U.S. Military Academy at West Point in 2020, on the eve of his 74th birthday.

Trump consistently attacks Biden over his age and stamina, despite the former president only being roughly three-and-a-half years junior to the current steward of the Oval Office.

Experts: Biden, Trump show signs of being 'SuperAgers'

Experts, like S. Jay Olshansky, a public health professor at the University of Illinois at Chicago, says both men exhibit signs of being in good health despite clumsy moments.

"There's no evidence to indicate that their age is getting in the way of the decision-making that is going on," Olshansky told Spectrum News.

Olshansky, an expert in estimating lifespan, says Biden and Trump show signs of being what's known as a "SuperAger" — a term Northwestern Medicine describes as an individual over 80 who possess "the mental faculties of people decades younger."

"A SuperAger is somebody who makes it past the age of 80 cognitively intact and usually operating 10 to 20 years younger than their chronological age," Olshansky said.

Dr. Sandra Weintraub, a neuropsychologist at Northwestern University, says all signs from their very public lives indicate that both Biden and Trump would pass the memory test that determines SuperAgers, and notes that age alone doesn't determine fitness to serve.

"The deciding factor is: How is your mind? How is your brain?" Weintraub said.

Both experts said there's no scientific evidence to suggest that the old adage that presidents age faster while in office is true. While they agreed that aging does carry more risks, not everyone does so at the same rate.

"Just because you're 80 years old, you can expect that you're not going to do as well as you're 70," Dr. Weintraub said. "But you really need to show where somebody is at that point in their life as opposed to assuming that they have followed the normal trajectory."

"There's evidence to suggest that Biden is not actually 80 years old," says Olshansky. "Chronologically he is, biologically probably not. The same thing would hold true for Trump."

Could focus on health, perks of the job help?

Elaine Kamarck previously served in the White House during the Clinton administration. Now a senior fellow in Governance Studies and director of the Center for Effective Public Management at the Brookings Institution, Kamarck has studied aging and the presidency.

She says that while presidents have grueling schedules, the perks of the job help them focus on the most important matters.

"Presidents of the United States don't have to worry about their laundry, their dry cleaning, their grocery shopping, right?" she told Spectrum News. "There's a big, big number of people taking good care of them."

That could be one explanation. Another could be that recent presidents have made an effort to emphasize fitness and health.

Bill Clinton was often spotted jogging and was very open about diet and exercise (and despite a famous love for McDonald's, in later years he's switched to a plant-based diet). George W. Bush was an avid runner (he completed the 1993 Houston Marathon in 3:44:52 prior to his White House tenure). Barack Obama kept up with his avid workout routine while serving as president.

And Biden is one of many Americans who enjoyed Peloton workouts during the COVID-19 pandemic.

Trump is the outlier to this trend, and has bragged about not working out. His campaign declined to comment for this story.

Biden's campaign points to his phyiscal activity, and says that there's an upside to his age, declaring it brings "wisdom and experience."