Joe Biden could become the oldest president to seek a 2nd term. Does his age really matter?

In 1980, journalist Jeff Greenfield predicted on television that Joe Biden might one day challenge Ronald Reagan if the Republican president-elect sought a second term.

Walter Cronkite didn't agree and when the 1984 election rolled around, Biden wasn't on the ticket. Voters chose to re-elect Reagan, then 73, and already the eldest American president to serve.

Two failed presidential bids would later come and go for Biden. But it wouldn't be until 2020 that he became a president-elect, shortly before his 78th birthday.

"We never had a president who served in office who was over 80," said Greenfield.

Until Biden, that is — who turned 80 last November and is now himself the country's oldest-ever president. He's expected to soon reveal if he'll seek a second term.

A second Biden victory would put the U.S. president on a relatively short list of leaders of democratic nations whose ascent — or return to power — came so late in life.

Yet experts say Biden should not be written off simply because he's older than some voters would prefer.

"The claim that Biden somehow is unfit [because of his age] just doesn't stand up," said Rodney Loeppky, an associate professor in the department of politics at Toronto's York University.

"He's up against a lot of cultural and political biases, and then he's also vulnerable to political attacks. But if you ask me objectively, you know, is he too old for the office? There's just no reason to say that."

Not just Biden

Biden is the oldest of the leaders of the G7 nations, though there are democracies currently led by political veterans of similar age and experience.

Last fall, Brazilian voters returned Luiz Inacio Lula da Silva to power at age 77, two decades after he first held the same job.

Israeli Prime Minister Benjamin Netanyahu, in his sixth term as leader, will turn 74 this fall, while India's Narendra Modi — in the midst of a second term as prime minister — will turn 73.

Other countries require a longer turn through the pages of history to find comparable examples.

In Canada, the most recent prime minister of similar age to Biden was Louis St-Laurent, who was 75 when the Liberals lost the 1957 general election. But that was at the end of his tenure in power, not at the beginning.

In Britain, only a handful of prime ministers have led the government as octogenarians.

The most recent was Winston Churchill, when he returned to power in post-war Britain in 1951. He was 80 when he left office in 1955. The Conservative prime minister was the oldest to lead his country in decades at that time and the oldest since.

By contrast, Rishi Sunak, the 42-year-old current prime minister, is the youngest British leader in 200 years.

The job can be tough on world leaders of any age, though, and may affect their health even after they leave office.

Anupam Jena, a physician and a professor of health care policy at Harvard Medical School, took a look at this issue in a 2015 observational study that compared the lifespan of hundreds of world leaders against the people who ran against them, but didn't get the job.

The study found "heads of government had substantially accelerated mortality compared with runner-up candidates."

And while Biden may already be 80, Jena said the U.S. president appears to be in good health — and his health may differ substantially from an average person of the same age.

"This is a vigorous man who's very active," said Jena, noting that Biden, as president, has access to a level of health care that few others do.

More generally, Alison Chasteen, a professor of psychology at the University of Toronto, said "there's a lot of variability with aging" and someone shouldn't be ruled out from doing a particular job simply because they are an older person.

"We know that chronological age, alone, isn't really a great indicator of a person's capabilities in later life," said Chasteen, an expert on age stereotypes and ageism.

A recurring question

The topic of Biden's age has been raised by political opponents throughout his presidency — including after his recent state of the union address.

Political observers predict Biden's age will continue to be pointed to, should he move forward with plans to run again.

Lindsay Chervinsky, a presidential historian, told The Associated Press that Biden's age is "the X factor" that differentiates him from his predecessors.

"If he was 10 years younger, none of these conversations would be happening," she said.

Yet Greenfield said the U.S. may be growing more accepting of seeing older people in such roles in the White House, noting the most recent election saw two men in their 70s — Biden and his predecessor, Donald Trump — vying for the job.

"What is in Biden's favour is that the country has gotten older," said Greenfield, referring to its aging population.

The University of Toronto's Chasteen said there are longstanding, negative stereotypes in many societies about what older people are capable of.

Seeing Biden act in the role that he does could help dispel such stereotypes, but Chasteen said the way the media covers his presidency can impact that — such as when a presidential stumble on airplane stairs was caught on camera a couple of years ago.

"That got a lot of media attention," said Chasteen, noting that when such "errors or mistakes" are explicitly linked to aging, that makes is harder to convey that a person "is doing his job competently and is aging very well, overall."

An expected line of attack

York University's Loepkky said Americans invest a lot in the individual leading their country — and that leads to scrutiny about a candidate's personality and suitability for the job.

"There's this personalized element to the to the presidency and age comes into that," said Loeppky, currently a Canadian Fulbright Research Chair in Race and Health Policy at the University of Memphis.

But he said it's also a topic that some Republican opponents are using on a tactical basis amid a vitriolic political climate.

"Age is one way in which they can ... dehumanize Biden and make him seem smaller in the face of that office," Loeppky said.

Paul Quirk, a professor of political science at the University of British Columbia, said Biden carries "enormous amounts of experience" to his daily job in the White House, stretching back to his time as a senator and vice-president.

With that in mind, he predicts that if Biden seeks a second term, "his age will be mentioned adversely from time to time, but I don't think it'll be a pivotal factor in the election."

Quirk, a specialist in U.S. politics, also noted that the style in which a president works can vary widely and be adjusted as per the preferences of the leader — as seen in the differing styles that prior Oval Office inhabitants have displayed.

"If a president slows down and is not able to work such long hours, that's not important," said Quirk, noting a White House leader has an array of staff to delegate tasks to as necessary.