Hillary Clinton’s Got This Something truly crazy would have to happen for Bernie Sanders to win the Democratic nomination.

To borrow a phrase from Dan Rather, Hillary Clinton swept through the South like a big wheel through a Delta cotton field on Super Tuesday. She won seven states total, including Alabama, Arkansas, Georgia, Tennessee, Texas and Virginia in the South. She also won Massachusetts and American Samoa. Bernie Sanders emerged victorious in four states (Colorado, Minnesota, Oklahoma and Vermont), but his victories tended to come by smaller margins and in smaller states. The end result is that Clinton has a clear path to winning the nomination, and Sanders’s only hope to derail her is for something very unusual to happen.

We’ve now seen 15 states vote in the Democratic contest, and it’s clear that Clinton’s coalition is wider than Sanders’s. Sanders has won only in relatively small states where black voters make up less than 10 percent of the population. That’s not going to work this year when black voters are likely to make up more than 20 percent of Democratic primary voters nationwide.

On Tuesday, we saw why. As she did in Nevada and South Carolina, Clinton won huge margins of black voters. Her worst performance was in Oklahoma, where 71 percent of black voters in the Democratic primary chose her. In Alabama, she won 93 percent of black voters on her way to winning 78 percent of Democrats overall. Clinton took no less than 64 percent of the overall vote in the Southern states she won.

It wasn’t just black voters, either: Clinton dominated with Hispanics in Texas. There had been some questions about how Hispanics voted in Nevada, but there was little doubt in Texas. The exit poll showed Clinton with a 42 percentage point win among Hispanics, about the margin she won in counties such as Hidalgo, where Hispanics make up 91 percent of the population. Those results bode well for Clinton in states such as Arizona, California, Florida and New Mexico.

The end result is that Clinton will now have a substantial delegate lead. When I wrote on Saturday that Clinton was on her way to winning the Democratic nomination, I projected that she would win 508 delegates on Tuesday. It will take a little while to get the exact delegate totals, but FiveThirtyEight contributor David Wasserman projects Clinton to win well over 500 delegates. That will give her a lead of around 200 pledged delegates, not counting her large lead among superdelegates.

This lead is pretty much insurmountable. Democrats award delegates proportionally, which means Sanders would need to win by big margins in the remaining states to catch up. He hasn’t seen those kinds of wins outside of his home state of Vermont and next-door New Hampshire. Consider the case of Massachusetts: My colleague Nate Silver’s model had Sanders winning the state by 11 percentage points if the race were tied nationally and by 3 points based on the FiveThirtyEight polling average last week. Instead, Sanders lost by nearly 2 percentage points.

Sanders needs a fundamental shift in the race. Unfortunately for him, it’s already a two-person affair — not like the Republican side, where we wonder how the race might change if one of the candidates dropped out. The votes on the Democratic side so far have been fairly predictable based on demographics; it just so happens that those demographics favor Clinton.

Sanders, perhaps not surprisingly, has indicated that he’ll continue to fight for votes across the country. But for every win he may get in mostly white states, Clinton will be marching toward the nomination with likely victories in states such as Michigan and Florida. The math indicates that Clinton eventually will win the nomination with relative ease.

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