Listening to the commentary last night, one might have thought he already won the November election.

In truth, as anybody with elderly relatives knows, those of advanced age can have good days and bad days. It’s not surprising to me that with sufficient preparation and rest (Biden didn’t give victory remarks after Super Tuesday, for instance) Biden could still deliver a political speech. But the concerns about his age are not about one speech — they are about how he will perform day after day, under stress, facing long and sleepless nights and crises, and in unscripted moments. It’s about how he will perform in one of the most demanding jobs in the world for nearly five more years if reelected.