If Biden should drop out, why shouldn't he resign?

The private and public calls by Democratic politicians and liberal media pundits for President Joe Biden to drop out of the race lead to an obvious question: If Biden should drop out of the race, why should he not also resign from the presidency?

Along with the private panicking by Democratic politicians and operatives who want Biden to step aside, several in the media are publicly calling for the same. That includes the New York Times editorial board, which said Biden is clearly “not the man he was four years ago” and he struggled to do everything during the debate, including “more than once, he struggled to make it to the end of a sentence.”