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 thatJoe 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 theticket.Voters chose to re-electReagan, then 73, and alreadythe 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," Greenfield said.

Until Biden, that is who turned 80 last November and is now himselfthe country's oldest-ever president. He's expected tosoon 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 topower came so late in life.

Yet experts say Biden should not be written off simply because he'solder 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, although there are democraciescurrentlyled by political veterans ofsimilar age and experience.

Last fall, Brazilian voters returned Luiz InacioLulada Silva to powerat 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 Modiin the midst of a second term as prime ministerwill turn 73.

Other countries require a longerturn 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 75when the Liberals lostthe 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 ministershave 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 ministerwas 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 worldleaders of any age, though, and may affecttheir healtheven after they leave office.

Dr. AnupamJena, 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 thepeople who ran against them but didn't get the job.

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

And while Biden may already be80, Jena said the U.S. presidentappears to be in good health and hishealth may differ substantially from an averageperson of the same age.

"This is a vigorous man who's very active," Jena said, 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 that "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 afterhis 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.

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

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

Yet journalist 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 Trumpvying for the job.

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

The University of Toronto's Chasteen said there are long-standing, 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 Chasteensaid the way the media coverhis presidency can impact that such as when a presidentialstumble on airplane stairs was caught on camera a couple of years ago.

"That got a lot of media attention," Chasteen said, 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 Loeppkysaid 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 presidency and age comes into that," said Loeppky, currently a Canadian Fulbright Research Chair in Race and Health Policyat the University of Memphis.

But he said it's also a topic that some Republican opponentsare using on a tactical basis amid avitriolic politicalclimate.

"Age is one way in which they can ... dehumanizeBiden and make him seem smaller in the face of thatoffice," Loeppky said.

Paul Quirk, a professor of political science at the University of British Columbia in Vancouver, said Bidencarries "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," Quirk said, noting a White House leader has an array of staff to delegate tasks to as necessary.