Jeff Greenfield’s deep dive into party rules and procedures, in Politico Magazine:

Whether or not President Joe Biden drops his bid for reelection amid rising pressure from party leaders, there’s a very good chance that the Democratic convention will be more contested than any in more than a half century….

That means that the convention rules, including who can vote on what ballot and how free the delegates are, will play a crucial, even decisive role. It requires a close look at a process riddled with tricky issues: delegates who are “pledged” but not necessarily “bound”;party insiders who cannot vote on the first ballot, except when they perhaps can; delegates who are free to vote their choice except when they can’t.

And all of these factors will lead to different outcomes depending on whether the convention will see an embattled president fighting a serious challenge to his renomination or a convention that must choose a successor to a president who has chosen to stand down. Further putting things up in the air is the early virtual roll call to nominate Biden that the DNC currently has planned, but which is being fiercely resisted by those who do not want a Biden nomination locked up before the convention even begins.