Congresman Gresham Barrett and State Representative Nikki Haley are running against each other. In the primary Haley earned 49% of the vote. In the runoff the candidate with the most votes wins. They are not required to defeat their opponent by a certain amount of votes.
The winner will face Democratic State Senator Vincent Sheheen in November.
Polls open at 7 a.m. and close at 7 p.m.