Harris headlined an annual event by the NAACP, the nation's oldest civil rights group, which included a prayer service and a march to the South Carolina House of Representatives in Columbia.

Harris said that freedom in the country is under "profound threat," citing the Supreme Court's overturning of Roe v. Wade, long lines for voting and the prevalence of gun violence. She quoted King's late widow, Coretta Scott King, who said "Freedom is never truly won. You earn it and win it in every generation."

Republicans, including that party's front-runner, former President Donald Trump, are wrapping up their Iowa campaigns on the day of their first nominating contest. The state is honoring King by "exercising true grassroots democracy," said Jeff Kaufmann, the chair of the Republican Party in Iowa.