In an earlier time, former South Carolina Gov. Mark Sanford would be all but certain victor against Democrat Elizabeth Colbert Busch, sister of comedian Stephen Colbert, in this week's special congressional election. But times have changed for the man who was once a rising Republican star,

The two are vying to replace former Rep. Tim Scott, who became a U.S. senator after Sen. Jim DeMint resigned in January, and are running in a heavily Republican congressional district. But the edge that Sanford should have has been wiped out by a string of widely publicized personal and ethical problems as governor.

In his effort to resurrect his political fortunes, Sanford now finds himself in the unenviable position of possibly being the first Republican to lose the disrict to a Democrat in more than 30 years. Analysts say his victory would have to be considered an upset.

Besides her opponents' problems, Colbert Busch has benefited from being the sister of Stephen Colbert, who brought her big donors and name recognition.

David Wasserman, who rates political matchups for the Cook Political Report, has labeled the May 7 election "the race you couldn't make up if you tried,"

Nathan Gonzales, deputy editor of the Rothenberg Political Report, ranks Colbert Busch as the favorite.

"We put the slight edge on Colbert Busch because in these special elections, momentum is critical and for a good stretch there, she had it and he didn't," Gonzales said. A poll done last month by Public Policy Polling, a Democratic-leaning pollster, gave Colbert Busch a 9-point lead.

The GOP considered Sanford a questionable candidate to begin with because of the issues already haunting him.

In 2009, then-Gov. Sanford disappeared for six days. His staff insisted that the governor was hiking the Appalachian Trail. But when a reporter cornered a returning Sanford at the airport, the governor admitted that he was actually in Argentina having an affair with another woman.

Sanford finished out his term as governor but was dogged by a charges of ethics violations and an official censure by the legislature for bringing "ridicule and shame" on the state.

Still, when the chance to run for Congress came up, Sanford jumped on it, winning a GOP runoff election and the party's nomination.

Then there was more trouble.

Soon after Sanford won a place on the ballot, court documents revealed that he had been accused of trespassing on his ex-wife's property. Sanford said he was merely visiting his 14-year-old son during the Superbowl, but Jenny Sanford said he violated their 2010 divorce settlement by entering her home. Sanford's poll numbers quickly dropped and he lost the financial backing of the Republican National Committee.

In recent weeks, Sanford has slightly closed that gap, analysts said, by highlighting Colbert Busch's acceptance of union money to fund a campaign in a right-to-work state.

Sanford is hoping his record as governor of cutting spending and lowering taxes, as well as his socially conservative philosophy, will resonate enough to help him squeak out a victory.

South Carolina political analysts aren't ruling it out.

"Despite Sanford's amazing and consistent missteps, he still has a shot," GOP strategist Lachlan McIintosh said. "The district is that Republican."