It's crunch time in the race to pick the Democrat candidate for president of the US. And with Super Tuesday looming, when 11 states will cast their votes, Hillary Clinton remains the frontrunner to get the nod. The reason is that despite Bernie Saunders' popularity, Clinton is the preferred of many black voters, who increasingly seem like the demographic who will decide the Democrat primaries.
Despite a strong showing from Sanders, the insurgent candidate from Vermont, in early, mostly white, states such as New Hampshire, Clinton is predicted to dominate in most states with larger black populations. In South Carolina, for example, which votes on 27 February, polls are putting her as far ahead as 28 points, simply because Sanders has failed to make any notable inroads amongst African-American voters.
So in a last-ditch bid to develop the kind of momentum which has seen him do so well with other left-leaning Americans, Sanders is turning to some of the US's black elder statesmen and celebrities.
Spike Lee, arguably the most prominent black film director in the US, much of whose work deals with race relations, chimed in on Sanders' behalf in a radio advert in South Carolina this week.
"Wake up. Wake up, South Carolina," he said, echoing the famous opening lines of his most famous film, Do The Right Thing. "Bernie was at the march on Washington with Dr [Martin Luther] King. He was arrested in Chicago for protesting against segregation in public schools. He fought for wealth and education equality throughout his whole career. No flipping, no flopping."
Sanders is hoping that hard-hitting endorsements like this might help chip away at Clinton's massive lead. He's also winning endorsements from prominent black academics, such as Dr Cornel West – an academic and political commentator who appeared in Matrix trilogy – and journalist Ta-Nehisi Coates, who won the US National Book Award for Nonfiction for his 2015 book Between the World and Me.
Coates, whose work focuses on contemporary American racial injustice, has blasted Bill Clinton's record with black issues from his time as president – on which so much of his wife's appeal with the community rests – blaming him for "some of the most disgusting legislation in terms of our criminal justice, in this country's history".
West, meanwhile, an active member of the Democratic Socialists of America who has held tenure at Harvard and Princeton, has openly endorsed Sanders on TV and on Twitter, saying "I endorse Brother @BernieSanders because he is a long-distance runner with integrity in the struggle for justice for over 50 years".
But it's on the youth vote of all races which Sanders is pinning most of his hopes. To this end, he's enlisted a growing roster of rappers. Killer Mike of Run The Jewels has emerged as a key booster for the Sanders campaign, carrying out strident attacks on Clinton and accusing her of taking the African-American vote for granted.
Hip-hop royalty Russell Simmons, meanwhile, co-founder of the iconic Def Jam record label, has also weighed in.
Sanders still has a mountain to climb; his support amongst black voters under 50 is less than 26% to Clinton's 60%. With voters older than 50, she leads 69% to 12%. Nevertheless, Sanders has the momentum in the race, and no-one is writing his chances off entirely, outside of South Carolina at least.