Coming out of a near-draw in Iowa and a landslide victory in New Hampshire, Bernie Sanders has momentum. But he’s heading into much trickier demographic terrain. Iowa and New Hampshire are among the the whitest states in America, not representative of the larger country and even less representative of the multi-racial coalition that makes up the Democratic Party. Sanders’s problem is that so far his “political revolution” has been much more popular with white voters than with Hispanics and especially with African-Americans. 

According to a recent PPP poll, Hillary Clinton leads among African-American voters nationally by a formidable margin, claiming 82 percent of their support compared with 8 percent for Sanders. The margins are much closer for white voters (Clinton’s 46 percent to Sanders’s 38 percent) and Hispanics (Clinton’s 48 percent to Sanders’s 36 percent). This popular support is bolstered by the daunting institutional backing Clinton enjoys from the Congressional Black Caucus and from leading figures in the black church. (Sanders does have the support of one member of the CBC, Keith Ellison.)

Black Americans are the essential firewall that keeps Clinton the presumptive front-runner in the Democratic race. As long as that firewall holds, Sanders has no pathway to winning the nomination. But the metaphor of a “firewall” suggests a level of security that Clinton may not actually have. As very recent history shows, it’s possible for that firewall to collapse.

For much of 2007, when Barack Obama was an unknown quantity, Clinton led among black voters and had the support of the black church and the black political class, notably Congressman John Lewis. As Jesse Jackson told The New Yorker in 2008, part of the initial skepticism was based on pragmatic concerns. “They didn’t know him, a), and, b), they thought it was a long shot,” Jackson said. “Black voters are comparatively conservative and practical.”

But it wasn’t just concerns about electability, which were greatly assuaged when Obama won the Iowa Caucus. It was also the fact that Obama initially presented himself as an aloof technocrat in the tradition of Gary Hart, someone who had little direct ties with the black community and with the tradition of the Civil Rights Movement. As Bob Moser reported in The Nation in 2007:

In a state where the Rev. Jesse Jackson’s wildly successful 1988 uprising still stands as a high-water mark for black political aspirations, Obama’s cool style and post-civil-rights rhetoric went over like a lead balloon in the early months of the campaign. The trouble was epitomized by a speech he gave to the legislative black caucus in April, where he offered his joking opinion that “a good economic development plan for our community would be if we make sure folks weren’t throwing garbage out of their cars.” To folks like Kevin Alexander Gray, who ran Jackson’s campaign here, this smacked not of fresh thinking but of “the oldest racial stereotypes. Translation: black people are dirty and lazy.” Obama’s middle-of-the-aisle message and delivery kept reinforcing black South Carolinians’ doubts about whether he was sufficiently one of them. 

Obama was able to transcend those doubts in South Carolina (and among blacks in general) when he started going to the black churches and speaking in the voice of prophetic social critique rather than technocratic problem-solving. Obviously, as a secular Jew, this would be harder for Sanders to do. Yet Sanders in his own way is a preacher, and his calls for a political revolution resonate with a deep tradition in black politics of challenging the status quo. 

While Clinton has the support of the black establishment, it’s notable that emerging figures like Killer Mike (who has endorsed Sanders) and Ta-Nehisi Coates (who has said he’ll vote for the Vermont senator) are coming on board. In a widely disseminated piece in The Nation, Michelle Alexander, author of The New Jim Crow, argued that Clinton doesn’t deserve the black vote, citing policies enacted by her husband—his crime and welfare reform bills, in particular—that badly hurt African-American communities. We are a long way from the days when Bill Clinton could plausibly be called the first black president. 

Sanders’s opening is that there is an upswing in black political activism growing out of Black Lives Matter and the crisis in Flint. Hillary Clinton has been quick to stand up for the residents of Flint and to reach out to Black Lives Matter, but given this newly militant strain in Democratic politics, her pragmatic approach to governance in general may not be a good fit. An important question is whether Sanders has the stomach to drive a wedge between Clinton and black voters, using critiques that could result in a very divisive (and possibly nasty) fight within the Democratic Party.

The black vote may be Hillary Clinton’s firewall, but she shouldn’t take that firewall for granted. In tonight’s debate, both she and Sanders need to make their case to black voters.