SUMTER, S.C. (AP) – The Bernie Sanders phenomenon has been driven almost entirely by white supporters. Now the Vermont senator is out to overcome hurdles with prospective black voters who are still learning about him and could shape whether his underdog campaign for the 2016 Democratic nomination can last.

Sanders, who organized sit-ins over segregated housing as a college student during the civil rights movement, must cut into Hillary Rodham Clinton’s advantage with African-Americans if he’s to do well in South Carolina’s February primary, where more than half the voters are expected to be black, and in other Southern states that follow in March.

Polls find the independent Vermont senator building a lead over Clinton in New Hampshire and closing the gap in Iowa, two mainly white states very much unlike the more diverse Super Tuesday states of Alabama, Georgia, Tennessee, Virginia and others.

The independent Vermont senator and his advisers say his policies and personal story can resonate among black voters, if the campaign can reach them. He says he plans to emphasize his personal efforts more as he campaigns, beginning this weekend with a swing through Georgia, South Carolina and North Carolina.

“I believe when the African-American community in South Carolina and around the country understands that I have one of the strongest civil rights records in Congress and was involved in the civil rights movement for many years before I went to Congress, they will respond,” Sanders said in an interview.

That would mark a shift from recent months. At several appearances in South Carolina in August, he drew overwhelmingly white audiences, and he hasn’t talked much about his civil rights past.

He’s been linking his policy proposals to challenges in the African-American community, citing dire economic statistics for blacks, blasting private, for-profit prisons and their role in incarceration of young black males, and bemoaning “institutional racism” and militarization of local police forces.

He stuck to that script Friday evening at an Atlanta fundraiser, his first event of a busy weekend schedule.

Sanders said emphasis on policy over his biography has been intentional.

Recounting his involvement with the Congress of Racial Equality and his arrest for protesting segregated housing at the University of Chicago in the 1960s, Sanders said he was “proud of the work” he did but “it’s not anything I like to brag about.”

“It’s much more important for me to tell people what I will do as president and how it affects them,” he said.

Still, he acknowledged that Clinton and her husband, former President Bill Clinton, have a long history with black voters, while Sanders has built his career in Vermont, where 95 percent of the population is white.

Clinton, who also has outlined proposals to address what she sees as the over-incarceration of black men, economic inequality and problems with access to voting, has already picked up support from top South Carolina Democrats, including two former governors and many black leaders.

One of them, 2014 Senate nominee Joyce Dickerson, argued that Sanders is too far behind to catch up.

“I called Bernie Sanders after my race, and no one ever called me back at all,” said Dickerson, a longtime councilwoman in Richland County, home to the state capital of Columbia. “I got more than 400,000 votes. If he’s not interested in my thoughts, in my list of voters, why should I be interested in him?”

Said Sanders: “We have a lot of work to do.”

The senator has emphasized his connections to black leaders in recent weeks and plans to campaign with the academic and civil rights leader Cornel West. Sanders met last month in Chicago with the Rev. Jesse Jackson, whom he twice endorsed for president in the 1980s.

Chris Covert, Sanders’ state director in South Carolina, said the campaign has 15 full-time staff members on the ground, with offices in Columbia and Charleston. More offices will be opening soon, advisers say.

“It’s not that the message isn’t resonating with the African-American community,” Covert said. “It’s that we haven’t communicated with them yet.”

After a rally in Sumter in August, Sanders backer Calvin Bennett, 44, said the candidate simply isn’t known.

“The African-American community, institutionally, has just been a part of the Democratic Party machinery for so long,” he said, explaining why he thinks Clinton, who is more closely connected with that machinery, has an advantage.

But Muhiyidin d’Baha, a lead organizer in Black Lives Matter of Charleston, praised Sanders for “his evolution” in how he talks about economic and social inequities. His group has no interest in endorsements, d’Baha said, but he argued that Sanders has an edge over Clinton.

“She is hopelessly compromised from years in this system,” d’Baha said, while Sanders, despite decades in public office, talks openly of “a political revolution.”