His hands caked in grime from his repair job, Walter Brown coughed out a laugh when asked for his thoughts about Bernie Sanders, whose insurgent presidential campaign has electrified liberals around the country.

“Who is Bernie Sanders?” he said while sitting on a bench during an afternoon break. Brown, 59, is already leaning toward Hillary Clinton and doesn’t plan to start researching other options.

“I don’t have time,” he said, gesturing toward the downtown building where he’s been working. “I’m here all day.”

Sanders’ effort to broaden his appeal beyond white progressives and young people has run into a roadblock here in the form of black working-class voters, who in interviews here this week repeatedly voiced their longtime loyalty to Clinton. Several echoed Brown’s point that they don’t have time to explore an alternative nor interest in learning about Sanders, a U.S. senator from Vermont who was practically unknown in South Carolina before launching his presidential bid.