NORTH CHARLESTON, S.C. — In 2008 and 2016, black voters in South Carolina’s presidential primary set the last two Democratic nominees on their way, backing Barack Obama and Hillary Clinton by huge margins. Rival candidates never managed to catch up in the race for delegates to clinch the nomination.
On Saturday, black Democrats are set to play a far different role in the state’s primary vote, coming to the aid of a candidate who is struggling, former Vice President Joseph R. Biden Jr. At the same time, it is unclear if that support will be enough to help him win in other states. Black voters are likely to split, perhaps sharply, along generational and ideological lines, and spread their votes across contenders, rather than coalesce once again behind a single candidate.
More broadly, in interviews with African-Americans across the state this past week, many said they were eager to send a message to the national Democratic Party: that their views on electability — which candidate is best suited to beat President Trump — would not be shaped by outcomes in the predominantly white states Iowa and New Hampshire, which backed former Mayor Pete Buttigieg and Senator Bernie Sanders in contests earlier in February.
“We’re the base, and we’re yet to express ourselves,” said David Cakley, a church deacon from Goose Creek, S.C, referring to black voters. “Biden needs a boost and we’re going to give it to him.”
Mayor Stephen K. Benjamin of Columbia, S.C., who has endorsed the former New York City mayor Michael R. Bloomberg, summed up the urgency for black voters in this primary by quoting a line from the Atlanta rapper André 3000: “The South got something to say.”
South Carolina signifies a turning point in the campaign: Candidates have been courting black voters in the state for more than a year, and now the Democratic hopefuls will see if their personal appeals and policy plans catch fire with the first predominantly black electorate to vote in the race.
Mr. Biden, who lost badly in Iowa and New Hampshire but improved in last weekend’s Nevada caucuses, is widely expected to win at least a plurality of black Democrats, with voters citing his familiarity with their concerns and his potential to appeal to moderate Republicans in a general election. But the margins may reveal fault lines around gender, age, regions and viewpoints.
Other Democratic hopefuls from across the ideological spectrum — liberals like Mr. Sanders and Senator Elizabeth Warren, as well as the billionaire Tom Steyer and moderates like Mr. Buttigieg — are aiming to demonstrate that African-Americans
“I see the momentum of Bernie, I see the number of black people for Biden, but I’ll be with Elizabeth Warren till she drops out,” said Herbert Bodison, a 65-year-old resident of North Charleston.
Shareef Boddie, a 23-year-old from Goose Creek, said he was torn among three candidates: Mr. Sanders, Mr. Biden and Mr. Buttigieg. He planned to make his decision on the way to the polls.
“I may go for Bernie Sanders, because he plans on relieving college debt from students. And that’s a big thing,” Mr. Boddie said.
The range of opinion is the electoral manifestation of the oft-repeated mantra “black voters are not monolithic.” But it could also curb the determinative power of black voters in the Democratic nomination process, considering that they have historically rallied around a single candidate, helping that contender grab all-important delegates in key congressional districts and providing an inside track to the nomination.
Rashad Robinson, president of the racial justice organization Color of Change, said black Democrats in this primary had done more than choose the winner: They forced the field of candidates to reshape how they discuss the black community.
“We’ve had a campaign season where people are calling out structural racism and saying ‘white supremacy’ on the debate stage,” Mr. Robinson said. “The fact that black people are being talked about in more nuanced ways — like black youth vote versus black baby boomers vote — it speaks to how much the movement building has been translated to electoral power.”
Mr. Darby, the Charleston minister, said he believed the whiteness of the Iowa and New Hampshire electorates affects how they view the primary’s central question of electability.
He contended that many white voters in those states could “afford” to base voting decisions solely on policy outlines and ideological promises, while many black voters were conditioned by history to assume the worst about politicians. He said he was not surprised that Mr. Biden was beaten by popular candidates in those states but was favored in South Carolina.
He compared Mr. Trump’s presidency to a house fire, and said black voters were better at recognizing the urgency.
“If your house is on fire, you don’t bring the decorators in to redecorate while the flames are still raging,” Mr. Darby said. “You put out the fire first — and then you redecorate.”