Since the idea of President Biden being “replaced” as the 2024 Democratic nominee was all the rage for a moment, I took the opportunity to explore the little understood mechanics of the issue at New York:

A byproduct of the panic over Special Counsel Robert Hur’s suggestion that President Joe Biden is an “elderly man” with memory issues has been media efforts to understand and explain how Democrats could replace the 46th president as their 2024 nominee, either with or without his consent. From a political perspective, the idea that Biden might be dumped from the ticket is extremely far-fetched. But technically it is possible, though increasingly complicated, right up to Election Day.

When it comes to changing horses in the middle of a presidential race, Democrats differ from Republicans in one fundamental respect: While GOP rules bind delegates to the candidates who win primaries or caucuses, Democrats have a moral rather than a legal obligation to remain faithful to their candidate. Fourteen states have laws that seek to bind delegates to the winning candidate, but it’s reasonably clear that party rules supersede such laws when they are in conflict. And in most states, delegates are released from their obligations if a candidate withdraws from the race.

Another difference between the parties is that Democrats have an established set of “unpledged” delegates who hold convention seats by virtue of elected or party offices they hold. These “superdelegates” don’t get to vote unless there’s a second presidential ballot. At the 2024 Democratic convention in Chicago this August, there will be 744 superdelegates out of a total of 4,532 delegates.

The idea that superdelegates might vote for anyone they want is largely fictional. They are chosen by campaigns to be 100 percent loyal to their candidate. This loyalty is even fiercer when the candidate is the incumbent president of the United States. There’s a reason no sitting president has been denied renomination if he wanted it since Republican Chester Arthur in 1884. So the idea that Democratic delegates are going to look at the polls in August and decide they can do better than Biden is nonsense; it’s not going to happen. Even if faced with the emergency of avoiding a Trump presidency, the Democratic Party will remain a coalition of interests and principles, not just a vehicle for winning one election.

But if Biden, for whatever reason, chooses to “step aside” — as a self-defenestration is euphemistically described — it’s another matter altogether. The problem for Democratic delegates won’t be liberating themselves to look elsewhere (with the possible exception of those from a few states with stricter “binding” statutes than others); it will be agreeing upon a successor. And the closer to the convention that this decision has to be made, the likelier it is that these 4,000-plus Biden loyalists will back whoever he designated as his successor. Fantasies of a President Gretchen Whitmer or Gavin Newsom or J.B. Pritzker or Pete Buttigieg or Michelle Obama notwithstanding, that successor will almost certainly be Vice-President Kamala Harris. Any other choice would not only infuriate Harris and her supporters; it would also retroactively label Biden’s first decision as party leader in 2020 as a mistake. For better or worse, the party will unite around its new leader; the Trump factor will, if anything, give Democrats an abiding hope of victory no matter how things look a few months out.

It is possible, I suppose, that Biden and Harris could decide to “step aside” together as an act of patriotic self-sacrifice and help design a spanking new ticket that’s dressed for success. But that’s more likely the stuff of potboiling novels from the kind of writers who pretend there are such things as spontaneous candidate drafts and moderate Republicans.

The cleanest Plan B scenario would involve some cataclysmic event happening to Biden that leads him or the party to reconsider his candidacy after the Chicago convention. In that extremely remote contingency, the Democratic National Committee would have the power to name a replacement nominee, just as it did in 1972 when vice-presidential nominee Thomas Eagleton “stepped aside” after revelations of DUIs and shock therapy. The DNC isn’t going to dump a renominated incumbent president, no matter how poorly he’s doing in the polls; back in the days when presidential elections weren’t almost always desperately close or vulnerable to post-election challenges and insurrections, one party regularly went to battle after Labor Day knowing it was likely to lose. But if Joe Biden cannot take up the cudgels for the last stages of a rematch with Trump (assuming the 45th president isn’t himself dumped for his vast record of misconduct, if not for some physical ailment), the party can quickly move on with Kamala Harris.