BELTON, S.C. — Heidi Trull does not usually allow customers to talk politics or religion at Grits and Groceries, her restaurant here in the farmland that defines the northwest corner of the state.

People’s opinions are usually too strong. And a heated argument can ruin a good dish of Carolina shrimp and grits.

But Friday afternoon, less than 24 hours before the state’s Republican presidential primary, her ban on political talk did not matter one bit.

No one had found a candidate they liked enough to argue for.

From country restaurants like this one to suburban shopping malls in Spartanburg and espresso bars in Greenville, voters facing four options in the Republican primary seemed to shrug and say, “I haven’t decided.”