The knock on President Joe Biden has become almost cliché.
He's too old. He mangles simple things such as riding a bike, reading cue cards, and putting on a jacket. It's time for him to pass the torch to a new generation of American leaders.
It's also not the first time a president's age — too old, or too young — has become a dominant theme in US politics.
Both sitting and aspiring presidents (and their running mates) have grappled with voters' concerns, reporters' questions, and rivals' barbs about the number of times they've orbited the sun.
To inoculate themselves against criticism, some have pledged to serve only one term or opened their health records for public examination. They've talked up their résumés and challenged their opponents' maturity.
Sometimes this worked. On occasion, the younger whippersnapper won anyway.
Here's a look at some of the previous White House campaigns where youth and experience went to war, all the way up to the nascent 2024 battle that could pit the two oldest presidents in US history at the time of their inauguration — Joe Biden and Donald Trump — against each another.