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.