If you pay attention to the news ahead of Super Tuesday, you’re likely to hear about a critical bar that the candidates face, a baseline test that could reshape the large field of Democrats seeking the party’s nomination.
It’s called the 15 percent rule, and here’s how it works.
What’s at stake?
Well, the nomination, of course. To get there, candidates must capture a majority of the 3,979 pledged delegates — 1,991, to be precise — at the convention this summer in Milwaukee.
During the primaries, the candidates are competing for two major pools of delegates.
One pool, known as at-large delegates, are allocated statewide; another, known as district-level delegates, are awarded by congressional district. In each case, a candidate must win at least 15 percent of the vote to be eligible for those delegates.
Candidates who fall short of the threshold statewide could still win district-level delegates if they capture more than 15 percent of the vote in a congressional district. But in a relatively large field, not everyone will be able to clear that bar in each state or congressional district, and those who don’t will be shut out.
The results could be significant in states like California, Super Tuesday’s biggest prize. It has 415 pledged delegates — 271 apportioned based on the results in the state’s 53 congressional districts and 144 awarded by statewide vote.
How are delegates awarded?
Delegates are distributed proportionally among the candidates who clear the 15 percent cutoff. With as many as seven candidates competing on Tuesday, several could pick up delegates, prolonging the race and making it harder for the front-runner to clinch the nomination.
“It’s very hard for winners to wrap up delegates,” said Elaine C. Kamarck, a senior fellow at the Brookings Institution and the author of “Primary Politics: Everything You Need to Know About How America Nominates Its Presidential Candidates.”
“The system tends to reward not losers, but second-place finishers, and that keeps the race going longer,” said Ms. Kamarck, who, as a member of the Democratic National Committee, could play a role in the process, as a superdelegate.
Already, some are concerned that the race could lead to a brokered convention for the first time since 1952, if no candidate hits the magic number of 1,991.
What happens to candidates who don’t clear the 15 percent threshold?
Candidates who fail to clear that bar in a particular state or district cannot win delegates there — and are locked out of the most critical part of the nominating contest.
Some could find their paths to the nomination all but blocked, as the cold reality of delegate math overtakes the bluster and spin used to paper over poor showings in early states. As these lower-tier candidates fall further behind in the hunt for delegates, donations could dry up and volunteers may quit.
The 15 percent rule, which was adopted in 1988, was designed to weed out candidates who don’t have a viable path to the nomination, Ms. Kamarck said.
“You have to shrink this somehow, right? And that’s what this was designed to do: Take out the smaller candidates,” she said.
What if just a few candidates clear the 15 percent bar?
The more candidates who fail to clear the threshold, the better it is for those who do. That’s because the votes of the failed candidates are effectively discarded when the delegate count is calculated. The math can significantly bump up the haul for the leading candidates.
For example, if only one candidate were to clear the bar in a given state or congressional district, even if he or she earned just 16 percent of the vote, that candidate would take home all the delegates in that area. If two or more clear the bar, they split the delegates proportionally, with the votes of the failed candidates excluded.
This could play out in powerful ways on Tuesday, when more than 1,300 delegates will be awarded — about a third of the total at stake in the entire nominating contest.
For example, a poll released on Friday by the Berkeley Institute of Governmental Studies found Senator Bernie Sanders of Vermont capturing 34 percent of likely voters in California’s Democratic primary.
Senator Elizabeth Warren of Massachusetts was the only other candidate to clear the 15 percent threshold, with 17 percent support in the poll. If that were the result on Tuesday, Mr. Sanders might only have to yield a relatively small portion of California’s at-large delegates to Ms. Warren.
“This situation gives Sanders an excellent chance of capturing the lion’s share of the state’s 415 pledged delegates,” the institute said.