Which is precisely why next Tuesday is shaping up to be very good for the senator from Vermont.

Over the next seven days, there will be almost 1,400 delegates awarded in more than a dozen contests across the country. That total is largely a function of the fact that California and Texas, two of the biggest states in the country, vote next Tuesday. In each state, there are two pools of delegates that will be awarded: one based on the overall statewide vote and one based on the results in each of the state’s congressional districts.

The math for awarding even the statewide delegates is somewhat complicated, so let’s use this Saturday’s contest in South Carolina as an example of how it will work. According to FiveThirtyEight’s average of recent polls in the state, former vice president Joe Biden has an advantage. He’s at 31.2 percent to Sanders’s 21.4 percent. The distribution of the average looks something like this.

We tweaked it a bit. Since the average doesn’t add up to 100 percent across the eight main Democratic candidates, for the sake of our example we distributed those leftover votes to those candidates proportionately to how they’re already polling. This isn’t how the vote will work, of course, any more than the polling below will perfectly capture the eventual results.

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The important number here is 15 percent. That’s the threshold at both the statewide and congressional-district level at which candidates are eligible for delegates. Only those candidates who hit 15 percent across South Carolina, then, get any of the 19 statewide delegates being awarded.

In our example, that limits the delegates to Biden and Sanders. From here, there’s an important shift: Delegates are awarded based on how much of the vote each gets among candidates who passed the threshold. So Biden gets about 59 percent of the vote among candidates who crossed the threshold. Sanders gets about 41 percent. So Biden wins 11 delegates (59 percent of the 19 statewide delegates at stake) and Sanders earns 8.

There’s a reason that Biden is poised to do well in South Carolina. It’s the first state to vote in which there will be a large population of black voters. In 2016, about 6 in 10 Democratic primary voters were black, according to exit polling. And Biden does well with black voters.

In fact, there’s a significant correlation between how dense the black vote was in 2016 and how Biden is polling in contests over the next week. There’s a significant inverse correlation between how dense the white population is and how well Biden does. This link is unusual; the only other significant relationship between race and support is for Sen. Amy Klobuchar (D-Minn.), who does worse in polling as the density of black voters increases.

South Carolina may be the first presidential primary that Joe Biden wins in his third bid for the presidency. It prompts any number of questions about how his campaign might have fared had the state come earlier in the calendar. Had South Carolina come before Iowa, where he stumbled, would we see his campaign in a different light?

Unfortunately for Biden, many of the states that will vote Tuesday aren’t as heavily black as South Carolina. Instead, Sanders leads in many of them, according to FiveThirtyEight — and passes the 15 percent threshold in each of the seven states for which there are enough polls to form an average. In some states, other candidates pass the threshold, too, but no one is set to pass it as consistently as Sanders.

The most important state of the seven shown above is California. As it stands, polling has only Sanders over the 15 percent mark — meaning he gets 100 percent of the statewide delegates. He currently has 43 delegates; being the only candidate to cross the threshold in California would immediately quadruple his delegate total from statewide delegates alone.

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Using the poll averages shown above and considering only statewide delegates, here’s how the next week would shape up.

Biden Bloomberg Buttigieg Gabbard Klobuchar Sanders Steyer Warren Current Current 13 0 26 0 7 43 0 8 S.C. S.C. 11 0 0 0 0 8 0 0 Calif. Calif. 0 0 0 0 0 144 0 0 Maine Maine 0 2 2 0 0 2 0 2 Mass. Mass. 0 0 0 0 0 17 0 15 Minn. Minn. 0 0 0 0 10 10 0 6 N.C. N.C. 12 12 0 0 0 14 0 0 Texas Texas 25 22 0 0 0 32 0 0 Va. Va. 10 11 0 0 0 13 0 0 Total Total 71 47 28 0 17 283 0 31

(Maine is a tricky example here, relying on an odd stipulation in party rules for allocating the delegates. You can read about it here; it’s the calculus used for the 3rd district in that example.)

Again, the existing polling averages will not perfectly capture what happens. But they do suggest key trends, including that Sanders consistently gets over the threshold. And therefore consistently gets delegates.

You’ll notice that some candidates fare unexpectedly poorly. Former New York mayor Mike Bloomberg, for example, would earn only 47 statewide delegates. He’s poured hundreds of millions of dollars into the Super Tuesday contests, suggesting an awfully poor return on investment. What’s more, he may have already peaked — suggesting he might do worse over the next week than expected.

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Let’s put a fine point on why this week could be good for Sanders. Remember: He needs to win just over half of the remaining delegates to clinch the nomination. If he falls off that pace, the percentage of delegates he needs to win will keep getting higher and higher. (I made a little interactive that explores this.)

If Sanders’s actual performance in the eight states above matches the polling average, he’s poised to win 63.2 percent of the statewide delegates in those states. Combined with the delegates he’d already won, he’d have locked up 59.3 percent of the delegates awarded before South Carolina and allocated based on the statewide vote in those contests.

Biden Bloomberg Buttigieg Gabbard Klobuchar Sanders Steyer Warren Now Now 13.4% 0% 26.8% 0% 7.2% 44.3% 0% 8.2% Statewide Statewide 15.3% 12.4% 0.5% 0% 2.6% 63.2% 0% 6.1% After Super Tuesday After Super Tuesday 14.9% 9.9% 5.9% 0% 3.6% 59.3% 0% 6.5%

That’s only about 400 of the 1,400 delegates that will be awarded over the next week, but winning big states means winning a lot of congressional districts, too. And winning across the board suggests that he’ll fare well in some of the smaller Super Tuesday contests as well.

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