On Monday, he is expected to join seven of his 2020 Democratic rivals in a King Day rally at the state Capitol, an annual event that began 20 years ago and has become practically mandatory for Democratic presidential candidates during election years as they try to win over black voters.

Other candidates also attended church services here in Columbia on Sunday morning. The only African-American candidate remaining in the race, Deval Patrick, the former Massachusetts governor, was offering remarks at nearby Bethel African Methodist Episcopal.

Both men were expected to attend a breakfast sponsored by the Urban League on Monday morning.

Campaigning on Sunday in Tulsa, Okla., the site of what is regarded as the single worst massacre of black citizens by their white counterparts in history, Michael R. Bloomberg, the former New York City mayor, recalled the slaughter of hundreds of African-Americans by white mobs in that city as well as in East St. Louis, Ill.; Elaine, Ark.; and Rosewood, Fla.

“In just that short period, from 1917 to 1923, more than 1,000 black Americans were killed by white mobs in cities and towns all across the country,” said Mr. Bloomberg, one of the few candidates who were not scheduled to appear this weekend in South Carolina as he pursues an unusual campaign strategy with a national focus. “But the truth is: What happened during that period was part of a continuum of violence that black Americans faced even after the end of slavery — violence that denied them their lives, their liberty and their pursuit of happiness.”

In South Carolina, Mr. Biden attended an oyster roast later in the day. A busload of surrogate campaigners had arrived earlier this past week, crisscrossing the state on a bus in what was called his “Soul of the Nation Tour.”