It’s not easy to figure out how the Democratic Party is going to allocate its delegates to the 2020 convention. I have had to use several sources to satisfy myself that I understand the rules, and I’m still a little fuzzy on some aspects. One fairly comprehensive source is The Green Papers, which does an excellent job of explaining how many delegates each state and territory will have– it includes the formulas and gives a best estimate of how the numbers will come out in the end. The problem with this source is that it does not satisfactorily describe how the delegates are going to be awarded to the candidates. To get a better sense of that, I went to the Brookings Institute and supplemented that will a good interview with Josh Putnam and a perusal of his site: FrontloadingHQ.

I’ve been meaning to take the time to do this for a while, and I was spurred into it by reading Ed Kilgore’s latest piece where he matches my intuition that the Democrats could really, truly be headed for a brokered convention. To get a sense of the odds of this happening, we need to have someone build a model. With a good model of the schedule, delegates, and allocation rules, we can test out different scenarios to see how often no candidate can achieve a majority of the delegates.

The heart of the problem here is a combination of a system built to winnow the candidates slowly, a new electoral landscape where money is less important than ever and the candidates can always generate at least social news, and way more declared candidates than the system ever envisioned.

The system winnows candidates slowly by having no winner-take-all contests. Instead, the delegates are awarded proportionately by congressional district and statewide vote, and the first place winner is likely to get no more than 60 percent of a state’s delegates. To get any delegates at all, a candidate must receive at least 15 percent of a state’s votes,  unless no one gets 15 percent, in which case “the threshold for receiving any pledged delegates drops to half of the vote share of the leading candidate.”

Needless to say, at a 60 percent maximum, you need to win a lot of states before you can assure yourself of securing an outright majority of all of the party’s delegates. Unless only one candidate is consistency getting better than 15 percent, this is going to be a very long slog until it’s officially over. Things get even sketchier if there are consistently three candidates clearing the 15 threshold, and even more so if they aren’t always the same three candidates. You can’t build a majority even by winning states if you aren’t getting a majority of the delegates and, while unlikely, it’s mathematically possible for six different candidates to simultaneously clear the threshold in the same contest.

I don’t expect current polls to mean anything by the winter of 2020 when the first of these contests will begin, but if we use the current polling leads of Joe Biden (29 percent in RCP avg.) and Bernie Sanders (22 percent), we can see how things could  work. Currently, no one else is topping the 15 percent threshold. So, the way it would work is that Biden and Sanders would trade delegates, some being awarded for winning states and others for winning congressional districts.  They’d split them somewhere between the range of 60-40 and occasionally someone else would pop up to take a few delegates making it harder for either of them to top fifty percent.  Even if one candidate was consistently trouncing the other, the fact that only two of them were splitting the delegates would keep the winner from building much of an advantage.  Still, this scenario should eventually produce a winner, even if we have to wait nearly to the end to see a mathematical elimination.

There are many other scenarios where people rotate through being above the threshold so that winner in one contest doesn’t even qualify for delegates in the next contest.  If there were to be three candidates who were trading wins with no single one of them consistently above the threshold, it would quickly become very difficult for anyone to get a majority.

In the past, candidates would drop out very quickly if they didn’t do well in Iowa, New Hampshire or South Carolina. This had nothing to do with delegates, and the only math involved pertained to dollars. It costs a ton of money to travel around the country with an entourage and put teams of workers in multiple states. No one could afford to do that without a sustainable influx of big money, and that money would disappear or fail to appear in the first place if a candidate did not have early success.  In our modern era, it’s much easier to sustain a campaign through either small donors or affiliated Super PACs. It’s also easier and cheaper to reach people with your messaging than it used to be when it was all expensive television advertising and crashing through media gatekeepers.   Candidates with social media accounts and a small but passionate base (or a major Sugar Daddy) can sustain their campaigns without early victories.  The upshot is that there isn’t going to be an aggressive culling of the field.

It could be that fairly early on the name of the game becomes simply to prevent anyone from getting a majority. In one sense, that’s always the goal, obviously, but people really could play more not to lose than to win.

Now, there’s one way that the nomination could end quickly, but for the reasons of proportional allocation I mentioned above I do not think it is likely.

Fifty-four percent of all pledged delegates will be chosen in the first five weeks of the primary season, mostly from four states — California, Texas, Ohio, and Michigan. An additional 10 percent of pledged delegates will be chosen one week later — nearly all from Florida and Illinois. One candidate with a big lead in name recognition or with a small band of intense supporters could wrap up the Democratic nomination based on the votes of a tiny share of voters and do so before primary voters have had much time to get acquainted with the candidates.

One feature of the allocation rules is that it is very difficult to come from behind and a lead of any size tends to be persistent. We saw this when Obama jumped ahead of Clinton in 2008 and when Clinton jumped ahead of Sanders in 2016. Both early leaders basically limped to the finish but without being legitimately threatened at all. Kamala Harris is hoping she can build a nice little lead out of California and then just ride it out. That’s a plausible scenario, and maybe Beto O’Rourke could do the same thing by winning big in Texas. This would be much more likely if another weird potential artifact of too many candidates comes into play:

These rules work well — ordinarily. But, when applied to the large candidate field looming for 2020, they carry two dangers. First, no candidate may win 15 percent of the vote. If that happens, the threshold for receiving any pledged delegates drops to half of the vote share of the leading candidate. The second and much more serious risk is that only one candidate narrowly clears the 15 percent threshold. Under the DNC rules, that candidate would win all of a district’s pledged delegates, even though 85 percent or more of the Democratic electorate preferred someone else.

If Harris were the only one to clear 15 percent in California or O’Rourke were to accomplish the same thing in Texas, they could basically win the nomination from that feat alone. No one could ever catch up without doing the same thing is a very big state (or two).

So, there are ways the nomination could be settled early, but not in a way anyone will find acceptable. More likely, it will grind out to the end and someone will get a majority. But it’s easy to see many scenarios in which a majority won’t be attainable.

In that case, the superdelegates will get to vote on the second ballot, which will make a consensus candidate the likely winner. That’s one reason why, even before I looked very closely at the rules, I argued that Joe Biden is the front-runner for the Democratic nomination. It’s not just that he’s ahead in the polls right now and unlikely to finish below 15 percent in any contests, it’s also that he’s the most natural consensus candidate if no majority is reached. He will pile up delegates as long as he stays in even if he isn’t winning, and he’ll be in a strong position at the convention if that is where it all gets decided.

But I wouldn’t worry too much about that prediction if you’re not a fan of Biden. The main takeaway from this piece should be that nothing about the upcoming election is predictable.