President-elect Joe Biden turned 78 on Friday. In exactly two months, he'll take the reins of a politically fractured nation facing the worst public health crisis in a century, high unemployment and a reckoning on racial injustice.
As he wrestles with those issues, Biden will be attempting to accomplish another feat: Demonstrate to Americans that age is but a number and he's up to the job.
Biden will be sworn in as the oldest president in the nation's history, displacing Ronald Reagan, who left the White House in 1989 when he was 77 years and 349 days old.
The age and health of both Biden and President Donald Trump -- less than four years Biden's junior - loomed throughout a race that was decided by a younger and more diverse electorate and at a moment when the nation is facing no shortage of issues of consequence.
Out of the gate, Biden will be keen to demonstrate he's got the vigor to serve.
"It's crucial that he and his staff put himself in the position early in his presidency where he can express what he wants with a crispness that's not always been his strength," said Ross Baker, a political scientist at Rutgers University who has advised legislators from both parties.
"He has got to build up credibility with the American people that he's physically and mentally up to the job." Throughout the campaign, Trump, 74, didn't miss a chance to highlight Biden's gaffes and argue that the Democrat lacked the mental acuity to lead the nation. Both critics and some backers of Biden worried that he was sending the wrong message about his stamina by keeping a relatively light public schedule while Trump barnstormed battleground states.
Some of Biden's rivals in the Democratic primary also made a case on age -- while skipping Trump's vitriol -- by raising the question of whether someone of Biden's and Trump's generation was the right person to lead a nation dealing with issues like climate change and racial inequality.
