What happens to candidates’ delegates when they drop out?

In the 48 hours after former vice president Joe Biden won a dominant victory in the South Carolina Democratic presidential primary, two of his competitors for the party’s nomination suspended their campaigns. Both Sen. Amy Klobuchar (Minn.) and former South Bend, Ind., mayor Pete Buttigieg joined Biden in Texas on Monday evening to offer him their endorsements before the state’s primary on Tuesday.

Those endorsements were important, though the effects are hard to evaluate at the moment. What may be more important are the 33 delegates that Buttigieg and Klobuchar have already won. Buttigieg finished in the top tier in both Iowa and New Hampshire, holding the lead in delegates briefly. Klobuchar parlayed a strong debate performance (largely targeting Buttigieg, incidentally) into a smaller pile in New Hampshire.

So what happens to those delegates now? What happens to delegates moving forward as candidates withdraw? The best way to answer that question is to look at the rest of the campaign in two parts: before and during the Democratic convention.

What happens before the convention
It’s worth quickly reviewing how delegates are allocated.

Most states hold primaries in which several pools of delegates are awarded as follows. (The process for caucuses ends up in the same place but with more cumbersome math.)

There are statewide delegates awarded to any candidate who finishes with more than 15 percent of the vote. Those delegates are distributed proportionally to the percent of the vote earned by each candidate crossing that 15 percent threshold. These are pledged delegates, meaning that they are expected to vote for the candidate who won them.