If Sen. Bernie Sanders (I-Vt.) can’t make inroads with black voters, his insurgent campaign won’t last long into the primary season. He made a stop in Columbia, S.C., on Friday. (Charlie Riedel/AP)

“We don’t know him.”

Carol Singletary got that response time and again in 2008 when she tried to sell her friends, family and other African Americans in her native South Carolina on underdog presidential candidate Barack Obama, who was competing with a seemingly invincible Hillary Rodham Clinton.

Now she is hearing the same about another Clinton challenger she backs: Sen. Bernie Sanders (I-Vt.), who visited South Carolina this weekend as he continued to surge among die-hard liberals and frustrated progressives — and struggle to connect with black voters.

Back in 2008, black voters in South Carolina, site of the first primary in a state with a significant African American population, eventually got behind Obama, abandoned the Clinton campaign and became a key bloc to help the then-senator win the Democratic nomination.

Singletary, who went on to help organize for Obama in Georgia, Pennsylvania and North Carolina in both 2008 and 2012, thinks South Carolina could do the same for Sanders — help put his long-shot campaign on the map and once again disprove the handicappers who say Clinton has a lock on the black vote. The staying power of the Sanders insurgency beyond the overwhelmingly white early contests in Iowa and New Hampshire probably depends on it.

But the raucous crowd at the Sanders rally Singletary attended inside a sweltering banquet hall in Columbia on Friday night highlighted the scale of that challenge. There were 2,800 people in the hall that evening — just a few dozen of them African American.

In some ways, Clinton, who has visited the state several times since launching her campaign, has a two-decade head start on Sanders.

Clinton and her husband, former president Bill Clinton, have both run here before, and many black voters have had the experience of voting or volunteering for three different Clinton presidential campaigns in South Carolina.

The past week was full of reminders of her advantage here. Ahead of Sanders’s arrival, Clinton campaign chairman John Podesta visited to meet with supporters at an event where former South Carolina governor Jim Hodges (D) announced his endorsement.

As Sanders spoke around the state, Clinton campaign surrogate James Carville was slated to spend the day meeting with local Democrats before officially launching her campaign effort here.

Clinton has visited South Carolina three times since announcing the campaign in April and has eight organizers working across the state. “Throughout this campaign, we have and will continue to meet African American voters whether they are — at their homes, communities, work or places of worship,” said Marlon Marshall, director of state campaigns for Clinton’s campaign.

Still, South Carolina was the site of the Clintons’ most high-profile stumble with black voters, when both made comments during the 2008 South Carolina primary season here that some said seemed dismissive and disrespectful toward Obama.

Singletary said some black voters still remember the Clintons’ missteps here during her last presidential bid.

“I don’t hold a grudge, but I haven’t forgotten,” Singletary said. “If she gets the nomination I’ll work for her, but not as enthusiastically as I would for Bernie.” Singletary, who works for a nonprofit group that seeks to reduce the rate of teen pregnancies, says she likes Sanders’s passionate call for fighting income inequality and expanding the social safety net.

Meanwhile, Sanders is largely unknown here, especially among African American voters. He has spent the past 30 years campaigning in Vermont, a state that is 95 percent white.

His most publicized interactions with African Americans on the campaign trail have come this year when Black Lives Matter activists disrupted his appearances at two events.

Shortly after one such incident earlier this month in Seattle, Sanders hired Symone Sanders (no relation), a young black woman who was involved in the criminal justice reform movement, as his national spokeswoman and released a position paper on racial justice.

In an interview with The Washington Post, Sanders acknowledged Clinton’s advantage with black voters, noting that her husband was hugely popular with African Americans and that she made her own connections with black voters during her 2008 presidential campaign.

But he said, as he has before, that once black voters get to know his background in civil rights activism, learn about his progressive record in the Senate and hear his campaign pitch for taking on the establishment, they will support him.

“I think, at the end of the day, when we have a terribly high unemployment rate among African Americans, when the wages paid to black families is too low to support a family, when black families have a hard time sending their kids to college, maybe they will say, ‘Establishment politics are not working that well for us, establishment economics are not working that well for us. Maybe it’s time to take on the establishment as Bernie Sanders proposes.’ ”

He isn’t leaning on his standard stump speech alone. He has on each stop in South Carolina decried the racism that led ­Dylann Roof to shoot nine black worshipers in June at a Bible study class in Charleston and has recited the names of several black men and women who have died in police custody — deaths that have fueled the Black Lives Matter movement.

Late Saturday, he visited Charleston, where mentioned the name of Walter Scott, an unarmed African American man who earlier this year was killed by a North Charleston police officer during a traffic stop.

Between campaign events here in South Carolina, Sanders met with groups of black leaders, including ministers and business owners, and visited with Black Lives Matter activists after his rally.

South Carolina isn’t obvious Sanders territory. The largest crowds to greet the Vermont senator in this more conservative state were in the 2,500-3,000 range, a fraction of the masses that turned out to see him during a recent swing on the West Coast, where he drew 28,000 in Portland and 27,000 in Los Angeles. And they were not much more diverse, even though African Americans account for half of the Democratic primary voters in the Palmetto State.

Symone Sanders introduced the candidate at each of his South Carolina events. ­“Hel-looooo, South Carolina!” she sang out, before giving a brief rundown of Sanders’s platform, including his calls for tackling economic inequality, reducing the prison population and making college education affordable for everyone.

It was, as the senator said, an agenda seemingly tailor-made for black voters — and many of the African Americans who attended said they liked what they heard.

That group included Joseph Sewell, 20, who frequently leapt to his feet, cheering, during Sanders’s speech in Columbia.

“Bernie Sanders is the only candidate I’ve seen who has tried to address systematic racism, income inequality and issues like corporate prisons,” said the University of South Carolina psychology major, who came to the rally with dozens of black and white classmates. “If I asked a Republican candidate about Black Lives Matter, they wouldn’t care. If I asked Hillary, she’d just say what’s convenient. I believe [Sanders] really cares.”

It’s reactions like these that give Singletary hope Sanders could win over enough black voters to make a difference here. “I believe with work it can be done,” Singletary said. “He’s not Barack Obama, so I think he’ll be a harder sell, but I think it’s possible.”

Correction: A previous version of this article misreported the location of the fatal shooting of Walter Scott. Scott was shot in North Charleston, not North Charlotte. This version has been corrected.