In general Biden seems to do best on issues that require either spine or simple glad-handing — holding firm against the generals who wanted to stay indefinitely in Kabul, keeping Republicans at the table for an infrastructure deal — but worse the more that success depends on a mastery of strategy or minute detail, or a careful negotiation between hostile factions.

Which shouldn’t be surprising since Biden’s inherent weakness is that he’s an old man, suffering from some manifest deficits relative to his vice-presidential self, in a job that devours younger politicians.

That makes a change of luck seem like the best hope for recovering his presidency, because it requires the least of him: Covid diminishes or vanishes; inflation is contained or temporary once economic normalcy returns; the immigration wave ebbs for cyclical reasons; the Democrats get their act together legislatively or don’t, but it’s a political wash either way.

Whereas what should worry Democrats most are scenarios that require a lot from this president: adaptability, finesse, a skillful use of the bully pulpit. Biden can definitely float back up; I’m less sure that he can claw his way back, as Bill Clinton did after his early-presidency stumbles.