[Update 11:46 a.m. Wednesdsay] Former Gov. Mark Sanford will compete against Curtis Bostic, a former Charleston councilman, in a runoff election in two weeks. The third place finisher, state Sen. Larry Grooms, conceded the race Wednesday.

[Update 9:30 p.m.] CNN projects former Gov. Mark Sanford will finish first in the Republican congressional primary, but short of the 50% needed to avoid a runoff. The second-place finisher, whom Sanford will face in the runoff, has not yet been determined.

[Update 9:02 p.m.] CNN projects that no candidate will reach 50% in the South Carolina 1st Congressional District Republican special primary, forcing a runoff April 2. One of the candidates is likely to be former Gov. Mark Sanford; the other has not yet been determined.

[Original post 8:45 p.m.] CNN projects Elizabeth Colbert Busch, a political neophyte and the sister of TV comedian Stephen Colbert, as the winner of the Democratic primary for a seat in the U.S. House representing South Carolina.

The First Congressional District seat opened up in December when Republican Rep. Tim Scott was appointed to replace outgoing U.S. Sen. Jim DeMint.

Sixteen candidates were seeking the Republican nomination for the House seat. Among them were former South Carolina Gov. Mark Sanford, trying to restart a political career that was derailed by an extramarital affair; Teddy Turner, the son of CNN founder Ted Turner; and state Sen. Larry Grooms, who has amassed some important conservative endorsements.