Tuesday’s vote follows three earlier Republican contests since June

South Carolina Republicans will return to the polls Tuesday for the fourth time since June to fill the U.S. Senate seat held by the late Lindsey Graham. The runoff will determine the Republican nominee for the full six-year term, with the winner advancing to compete in the fall general election.

Graham had won the June 9 Republican primary for renomination to the seat he first won in 2002. His unexpected death on July 11 from an aortic tear created a vacancy not only for the remainder of his current term but also as the Republican Party’s pick to compete for another six-year term, according to the Associated Press.

The finalists for the Republican nomination are Darline Graham, Lindsey Graham’s sister who was appointed to serve out the remainder of her brother’s current term, and Ralph Norman, a five-term congressman who ran for governor earlier in the year.

Neither candidate reached the majority threshold in the Aug. 11 special primary. Darline Graham placed first with about 33% of the vote, followed by Norman at about 25%. U.S. Rep. Russell Fry placed third with about 20% of the vote and has been eliminated from the runoff.

The runoff will be held Tuesday. The winner will become the Republican nominee for the full six-year Senate term and advance to compete in the fall general election.

The repeated returns to the polls reflect the unusual circumstances surrounding the seat. Graham’s June 9 primary win became moot when he died weeks later, prompting both a gubernatorial appointment to fill out his current term and the separate special primary and runoff process to nominate a candidate for the next six-year term.

Darline Graham entered the Senate as her brother’s interim successor. Norman, a five-term congressman, had run for governor earlier in the year.