Former South Carolina Gov. Mark Sanford (R) on Tuesday will face voters for the first time since his dramatic fall from grace — and it's expected he'll finish at the top of the heap in a GOP House primary.

Sanford, whose campaign has been equal parts fiscal ideology and apology tour, will likely win enough of the vote to make the GOP primary runoff, set for April 2. 

The big questions are whether he shows he has the strength to win the runoff — and which of the 15 other candidates he’ll face.

“He will make the runoff — he's definitely going to come in first. He has a solid core vote that stays with him,” said former state Sen. John Kuhn (R), one of the stronger candidates vying to face the former governor in the runoff. 

“The key is to come in second, because once you get in the runoff with him he's extremely vulnerable.”

Sanford became a figure of public ridicule in 2009 when he admitted to an extramarital affair with an Argentinian woman, after a disappearance from public view that aides first said was due to him hiking the Appalachian Trail.  

He returned to the national spotlight after declaring his plans to run in the special election for the Charleston-based House seat vacated by Sen. Tim ScottTimothy (Tim) Eugene ScottSenators demand cyber deterrence strategy from Trump CNN's Bakari Sellers: Democratic leadership is 'old and stale' Politicians, faith leaders react to passing of Billy Graham MORE (R-S.C.). 

Kuhn is one of the stronger candidates angling to carry the anti-Sanford banner in the a two-week runoff election sprint. 

The other serious Republican candidates, according to the campaigns, are state Rep. Chip Limehouse, state Sen. Larry Grooms, economics teacher Teddy Turner, the son of media mogul Ted Turner, and attorney Curtis Bostic.

Sanford has near-universal name recognition and enough funds to keep himself competitive. But the bizarre circumstances surrounding his extramarital affair and subsequent divorce remain an albatross around his neck.

If Sanford wins the primary, he could also face a tough general election in the Republican-leaning district. Democrat Elizabeth Colbert Busch, the sister of satirist Stephen Colbert, has coalesced the party around her and is putting up strong fundraising numbers.

According to various campaigns’ internal polls, Sanford is hovering around 35 percent of the primary vote, while his opponents range from the high single digits to just shy of 20 percent. 

All are battling to be the conservative alternative in the race. Sanford's first-round performance will shed light on whether or not he’ll be able to get the necessary 50 percent of support to win the second round.

Limehouse, Kuhn and Turner have spent the most on the race. All three candidates have been able to self-fund to some degree, and were on the air before the other candidates. 

South Carolina Republicans say that Bostic and Grooms have the most momentum. Bostic has tapped support from social conservatives and the evangelical community, while Grooms has wrapped up some big-name endorsements, including support from Reps. Mick Mulvaney (R-S.C.) and Jeff Duncan (R-S.C.).

“I'm the fiscally conservative alternative to Mark Sanford. The others may be touting that, but they don't have the credentials which is why I'm receiving local and national endorsements,” said Grooms.

“Bostic and I have been trending up and the others have been trending down,” he continued. “I think the negative campaigning is turning off a lot of voters. Bostic and I have run positive campaigns, I think that's part of it, and when people start tuning in to these commercials that have been running for a while I don't think they like what they're seeing. The top three guys have been spending heavily and ripping each other up. Bostic and I are now up on the air and running positive ads.”

Whoever emerges against Sanford is expected to have a strong chance at toppling him.

“I believe any Republican who gets in the race against him will beat him — the women are not voting for him,” said Kuhn. “How do you get to 50 percent in the runoff if you're missing half the vote?”

Even those close to the former governor admit it’ll be a tough fight, though they say it’s one he can win.

“Whoever the candidate is presents certain challenges. Once you get down to a two-person race and its one-on-one it's a lot easier to draw contrasts and distinguish yourself from your opponent. That's a lot harder,” said South Carolina state Sen. Tom Davis (R), a Sanford friend and supporter who has been his surrogate in some local debates. 

“The whole dynamic changes and becomes much more focused and sharp during the two-week runoff.”