Even the most ardent Biden supporter — and he’s not a man who inspires much ardor — can’t take seriously the idea of Biden as a two-term president. He would start a first term already older than Ronald Reagan was when he left office, and just two years from turning 80. The question will have to be asked sooner rather than later: will Biden acknowledge before the nomination is decided that he will be at most a one-term president?

Ah — but wouldn’t a one-term pledge be to his advantage? Republicans uncomfortable with Trump might be reassured: this would mean that after four short years of Biden, they could get what they really want, Nikki Haley or another establishment robo-Republican with Bush 3.0 software. And ‘woke’ progressives otherwise unhappy with Old White Cisgender Joe could tolerate him for four years, too, if he had a sufficiently radical running mate poised to replace him after 2024.

That all sounds plausible, except that voters really do take one election at a time. Biden 2020 is not going to be about post-Biden 2024. And a one-term pledge, or even an informal understanding that Biden will be a one-termer, concedes right here and now that Biden can’t cut it as a normal president. It amounts to an admission that not only will he be too old in four years’ time, he’s already too old.