Hillary Clinton was expected to win in South Carolina. She just wasn’t expected to win quite this big:

In South Carolina today, Hillary Clinton scored her biggest victory yet in the Democratic presidential primary. She beat Bernie Sanders by what looks to be nearly 50 percentage points thanks to overwhelming support from African-Americans.

Most polling had shown Clinton comfortably ahead of Sanders by about 30 points. Conventional wisdom suggested that a win of anything under 20 points would have been a sign of trouble for camp Clinton, while anything over 30 would have been an indication of at least a comfortable roll through most of Super Tuesday and quite likely through to the nomination.

But a 47-point win is something else altogether: a massive structural and demographic challenge that the Sanders campaign will need to reverse quickly to remain in consideration past Super Tuesday.

The demographics tell the tale:

According to the South Carolina exit poll, Sanders lost black voters 14 percent to 86 percent. That doomed him in a contest in which 61 percent of voters were black. If white voters were more supportive of his candidacy, Sanders might have been able to keep the race closer. But they split 54 percent for Clinton to 46 percent for Sanders.

Simply put, Sanders cannot win the nomination without doing more to win the African-American vote. Some states will be better for him than others, but the challenge of winning the nomination without performing far better with minority voters than he has so far will be too daunting to achieve.

Perhaps that will be the story of the campaign: that Sanders brought a more progressive message to what would otherwise have been a sleepy coronation, that he forced Clinton to adopt more progressive positions and rhetoric than she ever would have otherwise, but that ultimately the Clinton legacy combined with institutional support and a desire to continue in the tracks of the Obama Administration proved too great a hurdle for the insurgent campaign to ultimately overcome and win the nomination. Or perhaps South Carolina will be a demographic outlier.

In any case, the Sanders campaign will need to figure out how to solve its challenges with minority voters quickly or the Democratic nomination will be wrapped up shortly after Super Tuesday.

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Follow David on Twitter @DavidOAtkins. David Atkins is a writer, activist and research professional living in Santa Barbara. He is a contributor to the Washington Monthly's Political Animal and president of The Pollux Group, a qualitative research firm.