By Harriet McLeod
CHARLESTON, South Carolina (Reuters) - Former South Carolina Governor Mark Sanford, seeking political redemption after a sex scandal, won a runoff on Tuesday to become the Republican nominee for an open seat in the House of Representatives, setting up a May showdown against the sister of prominent political satirist Stephen Colbert.
Sanford beat his Republican opponent, Charleston attorney and former Marine Curtis Bostic, 57 percent to 43 percent, official results showed. He now faces Democratic nominee Elizabeth Colbert Busch in the Republican-leaning coastal congressional district's special election on May 7.
While serving as governor in 2009, Sanford disappeared for almost a week, telling aides he was hiking the Appalachian Trail when he was, in fact, visiting his mistress in Argentina.
After the news of Sanford's affair broke, his wife divorced him, he paid more than $70,000 in ethics fines and he was censured by the state legislature, though he served out the remainder of his term as governor. He is now engaged to marry the woman, Argentine journalist Maria Belen Chapur, who attended Sanford's victory celebration on Tuesday.
Colbert Busch's campaign said in a statement that "Sanford simply has the wrong values for our community," adding: "The families of this district need a representative who they can trust."
Sanford, who previously served in the House before being elected governor, said in a statement that his views and those of Colbert Busch "couldn't be more at odds with one another."
"My record is one of cutting debt, eliminating deficits, reducing taxes and working to make sure (businesses) are more competitive. On the other side, we have more of the same of what has gotten our country into the mess that it's in - a belief in government and government spending on things like the stimulus are a cure to all ills," Sanford added.
Both Republican candidates touted their fiscal conservatism and their opposition to same-sex marriage.
South Carolina Republican Party Chairman Chad Connelly described Colbert Busch as an overpaid "liberal darling" out of touch with local values.
The district, which was redrawn after the 2010 census, encompasses the city of Charleston and parts of four nearby rural counties and stretches south along the coast to include wealthy Hilton Head Island.
Republican Senator Tim Scott, who vacated the seat when he was appointed to the Senate, did not endorse a candidate.
Governor Nikki Haley appointed Scott to the Senate in December to replace Senator Jim DeMint, who resigned from office to head the Heritage Foundation, a conservative think tank.
Colbert Busch won the Democratic contest last month by a landslide, taking more than 95 percent of ballots cast. She touted her experience as director of sales for a shipping line and a leader in advocating science and math education in South Carolina.
Her brother is due to host two high-priced fundraisers for Colbert Busch's campaign this month in Washington and New York. Stephen Colbert is the host of the popular show "The Colbert Report" on cable TV's Comedy Central channel.
Her campaign has released internal polling that showed her leading Sanford by as much as 3 percentage points before Tuesday's Republican runoff. A Public Policy Polling survey released last week showed Colbert Busch leading Sanford with 45 percent favorability to Sanford's 34 percent favorability.
(Editing by David Adams and Will Dunham)