Former Gov. Mark Sanford won the GOP nomination in the special election, setting up a general election fight with Democrat Elizabeth Colbert Busch.
Sanford defeated attorney Curtis Bostic, 55 percent to 45 percent, in the GOP runoff, with 67 percent of precincts reporting, according to The Associated Press.
The 1st District is a strong Republican seat, but Sanford is not assured a general election win.
It is unclear how difficult the path ahead will be for Sanford in the general election. Some South Carolina Republicans insist that this is a solidly conservative district and that the idea of a Democratic winner is unfathomable.
But Colbert Busch, the sister of comedian Stephen Colbert, has put together a professional campaign. She even released an internal poll Monday that showed she had a narrow lead over Sanford. (Our own Stuart Rothenberg offered a skeptical analysis.)
There is a special election because the district's former congressman, Republican Tim Scott, was appointed to the Senate earlier this year. Gov. Nikki Haley picked Scott for the seat after then-Sen. Jim DeMint resigned from the Senate.