Both Democrats and Republicans are getting louder about old age as a reason to head off a rerun between President Biden, 80, and former President Trump, 76. Why it matters: Democrats tell pollsters Biden's age is a big reason so many want another nominee. And some in the GOP are using Trump's age to push the party past his divisive era. Haley called for a mandatory mental competence test for candidates over age 75 and declared: "America is not past our prime. What we're watching: Haley took the lead on the age argument, but many other younger Republicans are eyeing '24:Florida Gov.