CHARLESTON, S.C. — Beto O’Rourke used a two-day, 185-mile sprint through South Carolina last week in part to introduce himself to a powerful bloc of voters whose support will be pivotal to winning the Democratic presidential nomination: African-Americans.

From a crowded coffee house in Rock Hill — where the former Texas congressman spoke after visiting the iconic civil rights “Friendship Nine” lunch counter — to a town hall hosted by a prominent African-American state senator, O’Rourke tweaked his stump speech to emphasize issues of importance to voters of color, including criminal justice reform, economic fairness and improving access to education.

In stop after stop, O’Rourke called for the expungement of arrest records for marijuana possession, ending what he called the “schoolhouse-to-jailhouse” pipeline that treats students of color differently, and regularly noting that as a white man of privilege, he was still learning about the black experience in America.

In a state where the majority of Democratic ballots cast in 2020 will come from African-Americans, breaking through with black voters here will be pivotal to any candidate’s success.

"There has to be accountability,” O’Rourke told a questioner on the campus of South Carolina State University who asked about police killings of unarmed black men. “There’s a lot of federal money that goes to local police forces, that far too often has militarized these local police forces. I think that money needs to be contingent upon accountability, transparency, reporting on use of force and against whom force is used in our communities.”

At South Carolina State, a historically black university in Orangeburg, O’Rourke addressed the most diverse audience of his young campaign. And on a Friday afternoon, it was also among his thinnest crowds. Several students who remained till the end told NBC News that they credited the candidate for just showing up and listening.

"Just because a white man is running doesn’t mean he’s not going to get our vote,” said Herbert Smith, a sophomore business major. "If he continues to show his words to the black community — not just to the black community, but to the Latino community, and other people of different diversities — if he keeps on showing that love and support, he might just win.”

“For him to come to our community where some of us are actually voting for the first time, like myself, it gets me excited in a way,” said Ronitra Wilson, a freshman at next-door Claflin University.

That go-anywhere-the-votes-are approach is a solid one, Democratic strategist Joel Payne told NBC News.

"He needs to run as the underdog who needs every vote. African-Americans want someone who will vie for their vote and not anticipate support as a Democrat,” Payne said. "If Beto can do that he’ll be successful in South Carolina and across the country.”

O’Rourke has also pledged to diversify his campaign, telling an audience in Detroit that he wanted to ensure that his organization "looks like America, that women of color have leading roles of responsibility within this campaign.”

"I am absolutely intent on getting the most talented people in the right positions and ensuring that this campaign looks like America, and I think the only way, to your question, that you can hold me accountable for that is to see the team, and I hope to be announcing that team soon,” O’Rourke told NBC News on Friday.

O’Rourke has performed well with African-American voters in the past. In his closer-than-expected loss in Texas last year to Sen. Ted Cruz, the Republican incumbent, he won 89 percent of the African-American vote, and fully 94 percent of African-American women, according to exit polling.

In that race, O’Rourke earned plaudits from many African-American commentators and voters for his stirring defense of NFL players who kneel in protest during the national anthem.

But he is now running in the 2020 Democratic presidential primary, and instead of facing one seemingly vulnerable Republican, O’Rourke is competing against several candidates who see African-American voters as a key component of their potential path to victory, particularly Sens. Cory Booker of New Jersey and Kamala Harris of California, both of whom are black.

In his Senate campaign, and now in this one, O’Rourke has freely admitted he has a lot to learn about the needs and issues driving the black community. He has adjusted both his language and some of his policy views, including apologizing for a vote he took in 2017.

O’Rourke told reporters Friday that he made a mistake in voting for the “Thin Blue Line Act," legislation Mother Jones dubbed an “Anti-Black Lives Matter Bill,” which would have added the killing or targeting of police officers, firefighters and first responders to the list of aggravating factors in federal death penalty cases. O’Rourke’s 2017 vote broke with the majority of his fellow Democrats in the House, and came just two months after announcing his bid against Cruz.

“I do regret the vote and that was a poor decision on my part,” O’Rourke said Friday. “I’ve never supported the death penalty. You know, I think that attacking or killing a police officer should be an aggravating factor, but I don’t think that should contribute to taking somebody else’s life, and so that was a mistake on my part, and if I could have that vote again, I would not vote for it.”

Democratic candidates like Harris and Sen. Elizabeth Warren, D-Mass., have embraced the idea of reparations for black Americans affected by slavery. But O’Rourke doesn’t call for reparations — saying that American society needs to understand the historical context for modern racism, and directly address current racist systems.

An attendee at his appearance Friday at the University of South Carolina in Columbia asked, “Why should I, as a black man, vote for you when you oppose reparations?”

O’Rourke’s answer was extensive, calling slavery part of “the most foundational issue for this country," which was "literally built on the backs of slaves, those who were brought here in bondage from other countries against their will.”

O'Rourke often brings up civil rights activist Bryan Stevenson, who talks about bringing common history and facts about the country’s past to every American, while repairing structures and institutions within the country that are systemically racist — from the health care system to the education system to the criminal justice system.

“I think if we invest in fixing these institutions in this country, in ensuring a state like mine, and perhaps a state like yours, do not use racist voter ID laws to keep people from selecting their representatives — or racially gerrymander them out of their districts in the first place — if we ensure everyone who has a conviction, after they have paid their price, done their time can vote, can get ahead, if we expunge the arrest records for nonviolent drug crimes in this country, then I think we begin, just begin, to get to some of that repair,” O’Rourke said.

Contessa Davis, a freshman at the University of South Carolina, liked his response. “He didn’t just give a quick answer just for the sake of claps and applause, but he actually ran down the problems within our system right now in America and how he would go about bringing down those individual problems, not just saying, ‘Oh yeah, definitely reparations,’ but ‘This is what I want to fix,’” she said.

Other African-American voters at O’Rourke’s campaign stops say his approach is working.

"I think if he keeps talking to the people and being able to listen, and not talk at the African-American voters. Talk to us. Listen to what we have to say,” said Keisha Hensley, a small-business owner from Rock Hill. "As long as you listen and then actually put forward ideas that are legitimate ideas to do things, then he will be fine.”