Hillary Clinton delivered a keynote address at the Democratic National Convention in Philadelphia on July 28, 2016. (Michael Robinson Chavez/The Washington Post)

Now that we have the results from the first two contests in the Democratic presidential primary, it’s worth stepping back and again noting just how little progress the party has made toward selecting its nominee.

As of writing, the total delegates earned by primary candidates breaks down like this:

Candidate Iowa N.H. Total
Buttigieg 14 9 23
Sanders 12 9 21
Warren 8 0 8
Klobuchar 1 6 7
Biden 6 0 6

Those results may change, particularly in Iowa where the vote-counting has been a complete disaster. But nonetheless: We’re off and running!

That said, two contests in, we’ve barely made a dent in the number of delegates each candidate needs to secure the nomination. That happens when a candidate hits 1,991 delegates — meaning that Pete Buttigieg, a former mayor of South Bend, Ind., and the guy with the most delegates so far, has earned only 1.16 percent of the total he’d need to be the nominee.

That’s largely a function of the fact that the primary process begins with two relatively small states. The next two contests are a bit bigger, and then, on March 3, things go supernova. On that day, more than a third of the total number of delegates will be awarded.

And from that day forward, the Democratic nominating contest might be doomed to end in a contested convention. There are two rules intended to counterbalance each other as the primary process moves forward, and they may ensure that result.

The first is that delegates are awarded in each state proportionally. That’s why Sen. Bernie Sanders (I-Vt.) is in second place in the delegate hunt despite earning more support in both Iowa and New Hampshire. The way states allocate delegates differs, but because of proportional allocation, close contests result in each leading candidate receiving an equal share of delegates. Sanders beat Buttigieg in New Hampshire and tied him in delegates.

The other rule is the reason that neither former vice president Joe Biden nor Sen. Elizabeth Warren (Mass.) earned any delegates in New Hampshire. To win delegates, you have to pass a 15 percent threshold of support. Neither Biden nor Warren hit double digits in New Hampshire, so both were denied any delegates.

You can see how these might work together: proportional distribution but only for high-performing candidates. In a three-person race where one candidate earns 10 percent of the vote, she can’t play spoiler because she is locked out of the delegate hunt. In New Hampshire, a purely proportional allocation of the delegates would have meant three fewer delegates each for Sanders and Buttigieg — delegates they may need in June as they push toward 1,991.

The problem, though, is that the 15 percent threshold may not end up being high enough.

On March 3, 1,357 delegates are at stake. Let’s say that Sanders wins 35 percent support in each contest, Buttigieg gets 25 percent and former New York mayor Mike Bloomberg gets 20 percent. (No one else hits the 15 percent threshold.) Let’s assume, too, that they come into the day with 60, 30 and zero delegates, respectively. The three split the delegates proportionally.

Candidate Coming in On March 3 Total
Sanders 60 594 654
Buttigieg 30 454 454
Bloomberg 0 339 339

Fair enough. Sanders is now well on his way to the total he needs, right? Well, sure — except that there are a lot fewer delegates still on the table. After March 3, the remaining contests yield only 2,467 total delegates. So if Sanders needs 1,337 to clinch the nomination, he has to win 54.2 percent of the rest of the delegates.

Candidate Coming in On March 3 Total Needed
Sanders 60 594 654 1,337 54.2%
Buttigieg 30 454 454 1,537 62.3
Bloomberg 0 339 339 1,652 67

The problem accelerates with each contest in which he doesn’t hit the 54 percent mark. Even if he wins a majority of the delegates — say, 53 percent of them — in the next five days of voting (on which 1,198 delegates are at stake), he is still 734 delegates short of clinching. Meanwhile, only 1,269 delegates are left in play, and Sanders now needs to win 57.8 percent of them.

This was what doomed him in 2016. Hillary Clinton jumped out to a lead in the delegate count by running up big victories in the South. Sanders would win caucuses and primaries that narrowed her lead, but he kept falling short of the percentage he needed to be on track for the delegate majority. He had functionally lost the nomination by the middle of March, when he needed to win 58 percent of the remaining delegates to tie Clinton.

His efforts to keep Clinton from reaching the nomination threshold were actually hampered by there being only two candidates in the race. When that’s the case, a one-point win in California is about the same as a 20-point win in Vermont because of proportional allocation. Winning California by one point this year earns you 210 delegates — but in a two-person race, the other candidate would get 205 delegates. You moved closer to 1,991, but so did your opponent, by nearly the same amount. The flip side of the calculus, then, is that once you gain a significant lead in the delegate count, it’s hard to lose it. Four years ago, Sanders kept winning primaries and occasionally gaining some ground, but he never won blowout victories in big states, making the end result inevitable.

The Democratic system indirectly aided Donald Trump. The Republican nominating contest had some states in which delegates were awarded proportionally — but it had more in which either the winner got all of the delegates or the winner got most of the delegates. That meant that while Trump was earning less support from Republican voters than Clinton was from Democrats, he quickly earned a much larger percentage of the allocated delegates. He locked up his nomination before she did, despite her bigger lead in support from voters. That head start let him focus on the general election before she could.

It’s possible that a candidate could do much better on March 3 than simply securing 35 percent of the delegates in play. The field will be narrower by then; it’s easy to see how someone might walk away with 50 percent of the delegates. If they had no delegates coming into the day, though, even that candidate would need to win 53.2 percent of the rest of the delegates to clinch the nomination. A candidate needs 756 delegates after March 3 to clinch the nomination by winning only a majority of delegates moving forward.

Another possibility is that, as voting moves forward in April and May, the leading Democrat keeps seeing that magical percentage move further and further away. There may come a point, as it did for Sanders in 2016, at which there aren’t enough delegates left for a candidate to secure the nomination. Four years ago, that didn’t matter, because Clinton hit that mark. If the leading candidate this time reaches that horizon, though, the nomination comes down to voting at the party convention in July.

And Trump again benefits.