Here's the most important number for Hillary Clinton out of Tuesday night's primaries: 86.
That's how many delegates she won from the day's two contests, in Michigan and Mississippi. Her rival, Sen. Bernie Sanders, took 69, according to the count by the Associated Press.
So on a night when Sanders won the biggest headline -- an upset victory in Michigan -- Clinton padded her already big lead in the race to win a majority of the delegates needed to gain the presidential nomination at this summer's Democratic convention.
Primaries are about a lot of things: building coalitions, testing which issues mobilize voters, discovering a candidate's strengths and weaknesses. But ultimately, they're about one big thing -- math. And right now, despite the Michigan results, the math favors Clinton.
Through Tuesday night, about one-third of the delegates to the Democratic convention have been allocated. Clinton has won 759 to Sanders' 546. Those are the actual delegates awarded by voters and don't include the 712 so-called super-delegates, the party leaders and elected officials who automatically get to vote at the convention and who overwhelmingly favor Clinton.
Tuesday night's results illustrate why Clinton has built that lead in pledged delegates and continues to expand it: Not only has she won more states than Sanders, many of her victories have been landslides that have given her lopsided margins among the delegates. His victories have either been squeakers, such as Michigan, or have come in smaller states such as Vermont and New Hampshire.
Last night in Mississippi, for example, Clinton won more than eight-out-of-10 delegates, netting 25 delegates more than Sanders. By comparison, Sanders' narrow victory in Michigan won him eight delegates more than Clinton got.
What does all that mean for the next three months of primary contests?
All the Democratic contests award delegates proportionately to the vote the candidates get -- no winner-take-all contests on the Democratic side. So Sanders needs to beat Clinton, on average, by about 54%-46% in the remaining contests in order to win a majority of the pledged delegates. If he achieves that goal, he would then try to persuade the super-delegates to switch to his side.
That's not impossible -- Sanders has won bigger margins than that in some states, including Minnesota and Colorado. And as Sanders told reporters last night, his campaign believes that some of the states most likely to support him are yet to come on the calendar.
But with Clinton well ahead in polls of the biggest states set to vote next week -- Florida and Illinois -- the Vermont senator still faces an extremely tough road ahead.
For more on Campaign 2016, follow @DavidLauter
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