Throughout the nominating process, which began on Feb. 3 with the Iowa caucuses, votes in primaries and caucuses are really votes to elect delegates to the Democratic National Convention in Milwaukee in July. The goal for the candidates is to secure a majority of pledged delegates, and this cycle, the magic number to hit is 1,991.
Delegates are awarded at both the statewide and district – usually congressional – level. On the Democratic side, there are no winner-take-all primaries, meaning if a candidate wins a certain state, they don't just get all of the delegates up for grabs in that state. Instead, delegates are awarded proportionally based on the vote, but there's a key threshold all candidates must reach in order to be eligible to receive any delegates: 15%.
If a candidate nabs 15% of the vote either statewide or across a congressional district, or both, he or she will score delegates. Anything less – even 14.9% – and the candidate will come out of the contest with no statewide and/or district-level delegates, depending on where he or she missed the threshold.
What are the different types of delegates?
There are two main types of delegates – pledged and automatic or "superdelegates."
Pledged delegates are the ones allocated to presidential candidates based on the vote. The delegates themselves are real people, elected to pledge support to the candidate to whom the delegates are allocated to. While it may seem contradictory to the name, these delegates are not legally bound to support any candidate, but, they are presumed to be loyal to the candidate they were elected to support – and the presidential campaigns work hard to ensure the delegates elected to go the convention are ardent supporters of that respective candidate. There are 3,979 pledged delegates this cycle.
Automatic delegates – better known as "superdelegates" – are distinguished party leaders who become delegates by virtue of the office that they hold or held. These include DNC members, Democratic members of Congress, Democratic governors and distinguished party leaders – former Democratic presidents, vice presidents and majority leaders in Congress.
These delegates are also not bound to any candidate, and essentially have free reign to vote for whomever they want to. Some of these delegates are even candidates themselves, including the two front-runners this cycle, former Vice President Joe Biden and Vermont Sen. Bernie Sanders. Currently, there are 771 automatic delegates, but this number could change. If another Democrat is elected to Congress in a special election, or if a Democratic member resigns, for example, the number could increase or decrease.
How does a candidate win the nomination?
The rules changed after last cycle, and only pledged delegates are able to vote on the first ballot at the convention, unless a candidate has won enough pledged delegates that automatic delegates couldn't change the outcome of the vote if they were also allowed to participate. A candidate would have to secure at least 2,375.5 pledged delegates this cycle in order for automatic delegates to vote on the first ballot.
Securing the nomination before the convention will happen if a candidate wins an outright majority of pledged delegates, or if a candidate builds an insurmountable lead, and the remaining major candidates drop out. That person would then be the "presumptive nominee" – but they wouldn't actually become the nominee until the convention itself, where a roll call of delegates will take place.
If no one secures a majority of pledged delegates through the Democratic primary process, there could be a contested convention that would require multiple ballots to determine the nominee – something that has not happened since 1952. The rules on a second ballot and beyond are slightly different. If a nominee isn't secured on the first ballot at the convention, "superdelegates" then get to vote, and again on any subsequent ballot.
What happens to a candidate's delegates if they drop out of the race?
Four candidates who have won delegates have since suspended their presidential campaigns: Former New York City Mayor Mike Bloomberg, former South Bend, Indiana, Mayor Pete Buttigieg, Minnesota Sen. Amy Klobuchar and Massachusetts Sen. Elizabeth Warren.
By ABC News' current estimation, Bloomberg has 23 pledged delegates, Buttigieg has 26, Klobuchar has seven and Warren has 45.
So the big question now is, what happens to these delegates?
To reiterate: Pledged delegates are never legally bound to a candidate, but rather presumed to be loyal to the candidate they are elected to support at the convention.
If this process didn't seem complicated already, here's something to change that.
As noted already, pledged delegates are either allocated based on statewide results or based on district-level results -- and for the presidential drop outs' delegates, how they scored their pledged delegates matters.
About 35% of pledged delegates are allocated based on statewide results.
If a candidate ends his or her campaign – and, yes, even just saying you are "suspending your campaign" qualifies – before the actual delegates are elected to fill these slots, which usually happens sometime between April and June, the candidates' statewide delegates actually get reallocated, proportionally, to the candidates still running who also reached the 15% threshold in the state.
The remaining 65% of pledged delegates are allocated based on district-level results. These never get reallocated to other candidates, even if a candidate drops out by the time these delegates are elected, which sometimes happens before the statewide delegates.
"Those (delegates) are not reallocated. They just become very popular," is how a DNC official described this scenario to ABC News.
When a candidate drops out, he or she might say, "I'm endorsing XX, and I'm asking my delegates to support XX.” He or she might also just say, "I’m releasing my delegates." Again, campaigns do have a role in deciding who is elected to be their candidate's delegates – so the elected delegates, who are generally loyal to the candidate they are supposed to be backing, would be expected to listen to their candidate.
But, again, these delegates are in no way obligated to follow anyone’s direction – essentially making them "free agents" – and since these are real people, other campaigns will likely try to convince these delegates to back their campaign at the convention.
Enter a game of deal-making and other tactics to win over the district-level pledged delegates up for grabs.