Via Mediaite, she doesn’t mean they’re planning to replace her, just that they’re flipping through the party bylaws in case Hillary collapses on camera again. Because Jim Geraghty’s right about that — if she has another episode before November, she’s all but done. People can shrug off what happened yesterday on grounds that everyone gets sick now and then but protracted health problems over a span of weeks will be taken as proof that something serious and debilitating is going on behind the scenes. The left can spin as hard as it likes that she’s actually some sort of super-soldier, trudging through a grueling campaign swing despite having pneumonia. Voters aren’t going to gamble on a candidate who seems to be chronically ill. If there’s another fainting episode, Democrats should, and probably will, want her off the ticket. Whether the Clinton machine would permit that is a different story.

I don’t buy the theory either that Clinton’s unpopularity somehow neutralizes the concerns about her health because, when push comes to shove, we’d all prefer Tim Kaine to her if given a binary choice. Voters don’t like uncertainty. That may be the single biggest reason that Clinton continues to lead Trump despite having underwhelmed everyone. Trump is a loose cannon whose true political inclinations are murky; no one knows what he’d do if given real power. Clinton is dull, charmless, and corrupt — but predictable. If Democrats think they can pull the plug on her three weeks before the election, say, and imagine that voters will roll the dice on a candidate like Kaine whom many of them couldn’t pick out of a line-up, I think they’re kidding themselves. Trump, not Kaine, would become the “devil you know” candidate in that scenario. That’s why, if Hillary ends up too sick to continue, the only plausible substitute is Biden. Not only is he well-liked, he’s well-known. Voters could pull the lever for him knowing reasonably well what they’d be getting. In fact, if Biden was subbed in at the last minute, he might campaign explicitly on the idea that a vote for him is a vote for four more years of Obama. That’d be risky, but O’s job approval is higher right now than it’s been in years and minority voters would find it appealing. Biden could beat Trump head-to-head as a ninth-inning pinch hitter. I’m not sure any other Democrat could.

Even then, though, I wonder how long Democrats could wait to make the switch before it’s too late. If Hillary dropped out tomorrow and Biden stepped in, two months seems like time enough for him to establish his own brand. Every day the party waits beyond that makes the dynamic less comfortable (and increases the logistical difficulties, like replacing Clinton’s name on ballots with Biden’s). If there’s even a small chance of Hillary dropping out over the next two months, I would think Dems would want her out before the debates two weeks from now. A replacement candidate like Biden would desperately want and need that huge spotlight to (re-)introduce himself to voters. Although, for the same reason, the smart tactical play by Trump in that case would be to skip the debates, insisting that he prepared to face Clinton and that Democrats can’t be allowed to get away with a last-second switcheroo. Either way, Democrats are on the clock. If Hillary’s pneumonia is worse next week instead of better, to the point where she might have to skip the debates herself, they’ll have to think hard.

By the way, the Trump campaign has decided that it’s simply not going to comment on Clinton’s health, which is uncharacteristically restrained — and smart. There’s nothing Trump can say that voters aren’t already thinking about Hillary’s illness; commenting on her “stamina” or whatever will simply hand the media a way to make the story about him instead of her. It’s wise to sit back and let the public draw their own conclusions.