MOUNT PLEASANT — The face that launched a 5,000-mile trip made quite a splash.

The brief appearance of Mark Sanford's Argentine fiancee, Maria Belen Chapur, at his victory party Tuesday night quickly became the talk of Charleston, adding to the mystery of their relationship.

Sanford said her presence there was a surprise. She said nothing publicly but was affectionate and stood behind him as Sanford thanked his supporters. Afterward, she left quietly.

Those who were at Sticky Fingers said Chapur's cameo added to the novelty of the evening.

“I didn't have a problem with it; I had been kind of wondering when she was going to appear,” Sanford supporter Joann Knapp said.

By midday Wednesday, Sanford, who refers to his bride-to-be as Belen, did not want to discuss her role. His campaign said it is focusing on the rest of the 1st Congressional District race, and that she is visiting from Argentina only for a short while.

But with the dust settling from Tuesday's win, the question now is: How will her first public appearance at one of his events play with voters?

College of Charleston political scientist Kendra Stewart said Chapur's sudden presence probably helped much more than it hurt.

“This would have been very risky at the beginning of the campaign, but he had a pretty solid win,” she said, “which sends a message that voters have moved on and gotten over the affair.”

Sanford beat fellow Republican Curtis Bostic in Tuesday's 1st District GOP runoff by a 57 percent to 43 percent margin, according to unofficial returns.

Additionally, Stewart said Chapur's showing, coupled with the widespread media coverage of her face afterward, also helps him with female voters, a crucial demographic that Democratic opponent Elizabeth Colbert Busch hopes to claim in the May 7 election.

“It's easy to hate the 'other woman' when you don't see her or know anything about her,” Stewart said. “This gives a human face to the other woman. It will make it easier to identify with her and more difficult to judge her.”

Chapur was the woman the formerly married Sanford traveled to see in Argentina in 2009 by forging an elaborate lie, tainting his career as governor.

Other politicos said there is still room for caution. Scott Huffmon, a Winthrop University political science professor, said having her by his side is a gamble.

“There's the fear that it will simply serve as a reminder of his philandering,” he said. “On the other hand, it could be a subtle signal that this wasn't just some tawdry affair, but he was pursuing true love.”

Even Knapp said she had mixed feelings about Chapur's presence. “I don't want it to be a constant reminder, that every time a woman sees her it brings up that whole thing all over again.”

The Chapur appearance, if truly a surprise, runs counter to what campaigns normally do — try to control every aspect of the public show.

“Usually,” Stewart said, “these things are staged.”

Robert Behre contributed to this report.