CHARLESTON, S.C. — Four top Democratic presidential candidates promised black voters Saturday that, if elected, their administrations would help close the wealth gap between black and white Americans, continuing the growing trend of Democratic candidates and officials talking more explicitly about racial inequalities.

The candidates, former Representative Beto O’Rourke of Texas, Senator Cory Booker of New Jersey, Senator Elizabeth Warren of Massachusetts and Mayor Pete Buttigieg of South Bend, Ind., each asked a packed house of South Carolina Democrats to buy into a vision of how to lift up black communities, particularly regarding “work, wages and wealth,” the principal theme of the event.

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“This isn’t just about African-American communities,” Mr. Booker said. “You cannot have a large segment of the population denied equal access to markets or capital or health care, and not think that is a cancer that affects the body as a whole.”

Mr. Booker and Ms. Warren, whose campaign has been on the rise in recent weeks, both received standing ovations at the forum hosted by the Black Economic Alliance, a group formed in 2017 by black civic and business leaders.