From a Wall Street Journal books column by Matthew Rees headlined “‘The Big 100’ Review: Young at Heart, If Not Otherwise”:

If Joe Biden wins re-election next year, he will be 86 at the end of his second term. His age, alongside his miscues and mishaps, has prompted a few Republicans to recommend mental-competency tests for presidential candidates. But it’s not a partisan issue. More than two-thirds of Democrats say President Biden may be too old to serve again.