With Bernie Sanders climbing in the polls, many liberal pundits now see black voters as “Hillary’s firewall.” Even if Sanders wins in states like Iowa and New Hampshire, which have large white populations, these pundits say he’ll find his support plummeting in a state like South Carolina, where black voters are firm Clinton supporters.

But in 2008, Clinton saw that firewall in South Carolina quickly melt away after Obama’s victory in Iowa and his strong second-place finish in New Hampshire. And South Carolina representative Jim Clyburn, who is African American and one of the top Democrats in the House, has cautioned against the notion that black voters were solidly behind Clinton this time around.

Turns out, he was right. According to a poll released last week, support for Clinton in South Carolina is plummeting. Back in December, Clinton had a thirty-six-point lead over Sanders. That lead has been cut nearly in half: 47% of Democratic voters now favor Clinton; 28% favor Sanders. That’s still a lot of support for Clinton, but it’s considerably smaller than in December, when she had 67% of the vote.

Now it’s true that Sanders hasn’t gotten those defectors from Clinton. What seems to have happened is that a significant chunk of her supporters are reconsidering their support (Sanders’s support is nearly what it was in December). Which could mean many things. One possibility is that voters are waiting to see what happens in Iowa and New Hampshire, where Sanders is doing well.

But the most interesting part of the polls is the racial and gender breakdown of the vote: Clinton is losing a higher percentage of her black supporters than of her white supporters, and Sanders is making greater gains among women than among men.

On December 17, this is how the polls looked:

On January 22 (the poll was actually concluded on the January 15), this is how the polls looked:

Between December and January, we see major drops in support for Clinton among all categories of voters. But there’s a greater decline among black voters (30%) than among white voters (24% drop). There’s also a virtually identical drop among male (36%) and female (34%) voters.

Sanders’s support among black voters remains practically the same as it was in December (he sees a tiny drop among white voters). But more interesting is that while he’s made gains among both male and female voters, the gains among women (28%) are much greater than among men (13%).