Bernie Sanders couldn't have asked for a better electorate than the one he saw in New Hampshire. It was mostly white -- a group with which he does much better. It was 40 percent independents (same) and two-thirds liberal (same). It was the state next to his home state. It was a state he should have won big and a state he won big.

South Carolina was the same for Hillary Clinton.

According to preliminary exit poll data reported by CNN, the electorate in Saturday's primary voting was heavily African-American -- even more heavily black than in the 2008 election that gave Barack Obama a 2-to-1 victory. Exit polls suggest that black voters supported Clinton at a 4-to-1 margin.

In 2008, 78 percent of black voters supported Barack Obama to 19 percent who supported Clinton. This year, the preliminary figures suggest that Clinton did even better. What's more, 4-in-5 voters said that race relations were important in deciding their vote -- and about 7 in 10 of those voters picked Clinton.

It was also a more moderate electorate than the first three states -- though it was slightly less moderate than in the Democrats' two most recent contested nomination fights in South Carolina -- which itself keeps with the trend so far this year. About 7 in 10 moderate voters supported Clinton in South Carolina.

Seven in 10 voters also want to continue Obama's policies, versus moving in a more liberal direction. Guess what! They supported Clinton -- who has made a point of bear-hugging Obama -- at a 4-to-1 margin, too. Turnout among young voters appears to be about the same as it was in the state in 2008, but that's slightly lower than we saw in Iowa and Nevada. Those 65-and-over backed Clinton with 4 out of every 5 votes.

South Carolina was intended to be one of the bricks in Hillary Clinton's "firewall" against a Bernie Sanders surge. That was because of her strong support from black voters. An interesting rift has emerged, though, between young black and Hispanic voters and older ones. The former appear to back Sanders; the latter Clinton. That's particularly a problem for Sanders because younger voters turn out less heavily. The question from South Carolina, then, was if Sanders could make headway with non-white voters.

It seems not.

Last October, Sanders's strategist suggested that the candidate only needed to win 30 percent of the black vote in the state to win the state. He appears to have barely hit half of that. FiveThirtyEight estimates that, if national numbers on demographics were to hold, Sanders would lose South Carolina by 20 points. He appears likely to underperform against that measure.

This is a huge problem for Sanders moving forward because a number of large upcoming states are also ones with large non-white populations. If Sanders did worse than expected here, why would he do better than expected there? It's worth remembering that in the busy schedule over the next few weeks, Sanders won't have been able to spend much time on the ground, certainly not spending as much time with them as he did in Iowa or New Hampshire. And that the delegates will be allocated proportionately, meaning that if Clinton runs up the margins, she runs up the delegates, too.

We may be reading too much into a state on which Sanders had largely given up. But in the first big test of her support from black voters, Hillary Clinton made a dominant statement.