UPDATED 5:40 p.m. | Republican Mark Sanford will launch his comeback bid for Congress on Wednesday, a move he has telegraphed for weeks and which will make him the immediate front-runner in a crowded special election primary.

The former South Carolina governor represented the 1st District from 1995 to 2001, when he kept a term limits pledge and retired. He was elected governor in 2002. The coastal district is now open because GOP Gov. Nikki R. Haley appointed Republican Tim Scott to fill a Senate vacancy.

A tried-and-true fiscal conservative during his six years in the House and eight years as governor, Sanford gained a national and international profile for disappearing from the state for days in 2009 and then admitting to an extramarital affair with a woman from Argentina in a stunningly frank and emotional press conference. He had told his staff that he was hiking on the Appalachian Trail — which immediately became a punchline for comedians.

Still, the strengths he brings to the race are no laughing matter: name identification and access to a significant fundraising network. That’s likely to land him as one of the top two finishers in the March 19 GOP primary. If no candidate gets more than 50 percent of the vote, a runoff will be held April 2. Haley has set the general election for May 7.

The seat, which snakes along the coast from Hilton Head to north of Charleston, is comfortably Republican. Scott won re-election there with 62 percent of the vote in November.

Expected top-tier contenders include state Rep. Chip Limehouse; Teddy Turner, the son of TV mogul Ted Turner; state Sen. Larry Grooms; and former state Sen. John Kuhn, among others. Filing begins Friday.

Grooms will officially launch his bid Thursday. State Rep. Andy Patrick is expected to launch his run next week. The field is likely to grow even more crowded by the time filing for the race closes on Jan. 28.

But other candidates aside, the focus will be on Sanford and how he might chart a path to victory, weighted by his infidelities and the infamous disappearance.

“If he addresses the concerns of the people and shows a contrite heart and people believe him, I’ve seen more unbelievable things happen,” said former South Carolina Gov. David M. Beasley, a Republican. “South Carolina politics always prove to be interesting. It’s a sport down here. It’s a way of life.”