The most significant development in the Democratic primary over the past few days wasn’t Wednesday night’s slugfest of a debate in Las Vegas, entertaining as that was for anybody not in Michael Bloomberg’s camp. It was the publication of three separate opinion polls that showed Bernie Sanders with a substantial lead over the other candidates in California, which votes on Super Tuesday, March 3rd, now less than two weeks away.

The poll findings are important not only because California, the most populous state in the nation, carries a prize of four hundred and sixteen pledged delegates—more than a tenth of the over-all total of 3,979. The polls reflect how the Sanders campaign is growing in strength, ahead of the biggest day of the primary, and they also illustrate how the rules for allocating delegates could work to his advantage. Together, these factors place him in what is potentially a very strong position, even as the primary process is still at what seems like an early stage.

One of the three surveys, from Public Policy Institute of California, showed the Vermont senator with a whopping advantage of eighteen points—thirty-two per cent to fourteen per cent—over the second-place candidate, Joe Biden. In the other two surveys—from Monmouth University and SurveyUSA —Sanders’s lead was smaller but still notable: seven points and four points, respectively.

It’s unwise to place much credence on the results of a single poll, of course. But if you combine all three of the surveys and weight them according to their sample size, two key findings emerge: Sanders has about 27.4 per cent of the vote, and the only other candidates to cross the threshold of fifteen per cent are Biden and Bloomberg. (They both did it narrowly.)

Sanders’s ability to forge such a big lead in California reflects his strength among progressives, young voters, and minority voters, particularly Latinos—a coalition that may well lead him to victory in Saturday’s caucuses in Nevada. (He’s comfortably ahead in the latest polls there, too.) But the divided nature of his opposition and the fact that only two other candidates are at fifteen per cent are also important. Given the way the primary is structured, this could end up greatly amplifying Sanders’s victory, in terms of delegates awarded to him.

A key point to remember is that in California, as in many other states, the Democratic Party has decided that candidates won’t be allocated any delegates unless they receive fifteen per cent of the vote in a particular congressional district or fifteen per cent of the statewide vote. (Two hundred and seventy-two of the delegates are attached to individual districts, and a hundred and forty-four are tied to the statewide vote.)

To see how this system could work, imagine that the actual results in California replicated the findings of the Monmouth poll, which came out on Thursday. (That’s not likely, but the exercise is illustrative.) Elizabeth Warren, who was at ten per cent, and Pete Buttigieg, who was at nine per cent, could end with virtually no delegates at all. Meanwhile, Sanders, who was at twenty-four per cent, and Biden, who was in second place, at seventeen per cent, would receive an outsized allocation. “As the poll currently stands, it’s possible that only two or three candidates reach viability in any given congressional district,” Patrick Murray, the director of the Monmouth University Polling Institute, explained in releasing the new survey. “That would enable Sanders to rack up half the delegates or more while only earning one-quarter of the total vote.”

There wouldn’t be anything untoward about such an outcome. It simply reflects how the rules of the primaries have been laid down, and they apply equally to all of the candidates. But if you extrapolate from California to other states where Sanders is rising in the polls and the rules for allocating delegates are similar, it’s easy to see why many professional observers—inside and outside of the campaigns—believe that, by the end of Super Tuesday, Sanders may have racked up an irreversible lead in the number of pledged delegates.

“Since the contests in Iowa and New Hampshire primaries . . . Sanders has opened up a large lead over the rest of the field across Super Tuesday states,” Mitch Stewart and Dan Kanninen, two staffers on the Bloomberg campaign, wrote in a controversial campaign memo that was leaked just before Wednesday’s debate. “As the race stands today, Sanders is poised to leave Super Tuesday with an over-400 delegate lead versus his next closest competitor a likely insurmountable advantage,” the memo warned.

The other campaigns rightly slammed the leaking of this document as a brazen effort to put pressure on Biden, Buttigieg, and Amy Klobuchar—Bloomberg’s rivals in the moderate lane—to leave the race. After Bloomberg’s pitiful performance in the debate, it is perhaps he who should be considering an early exit. But the delegate math can’t be swept aside. The independent Web site FiveThirtyEight—whose forecasting model for the primary takes into account the latest polls and the method of allocating delegates, as well as other factors—also shows Sanders taking a lead of more than three hundred delegates over his nearest rival by the end of Super Tuesday.

To be sure, this analysis is based on recent trends continuing, which may not happen. A strong showing for Biden in Nevada, followed by a big victory in South Carolina, could alter the dynamic, as could a sizable bounce for Warren, after her strong performance in Wednesday’s debate. Even absent some major new development, Sanders is far from assured of getting a majority of the pledged delegates at the end of the process. Unless his vote share increases substantially from where it currently is in the polls, Sanders achieving such a decisive result seems like a stretch. Right now, though, the senator appears to have a very good chance of having a plurality of delegates going into the Milwaukee convention.