The crowd roared. Mr. Sanford said he had not heard what she said.

“She went there, Governor,” said Brendan Clark, a local news anchor and one of three moderators.

The special election on May 7 in the First Congressional District is the first time in several decades that a Democrat stands a strong chance of taking the seat in a district made up largely of moderate conservatives, many of whom are more moderate than the rest of the state.

For South Carolinians, more than 500 of whom packed an auditorium at the Citadel on Monday night, the debate was the first opportunity they had to watch the candidates faces off in what has thus far been a race big on drama and light on actual issues.

The drama, of course, centers on Mr. Sanford. His campaign began with several public apologies for mistakes he made in his personal life and a plea for redemption. He quickly shifted into making the race about his experience and strong fiscal conservatism, but in mid-April court documents surfaced that once again threw his personal life into the center of the ring.

Mr. Sanford’s ex-wife claimed that he had slipped into her house to watch the Super Bowl with their 14-year-old son in violation of court orders. She found him leaving the property, using his cellphone as a flashlight, and complained to the courts that he had violated their divorce agreement. The two are scheduled to appear in court on May 9, two days after the election, to resolve the issue.