An upcoming special election in Louisiana’s 5th District is shaping up to be the most unpredictable special election this fall, as a crowded field of 14 candidates from both sides of the aisle battle for two spots in a runoff election.

Operatives in the state say it’s a lock that conservative state Sen. Neil Riser will receive the most votes in the Oct. 19 primary and secure a spot in a Nov. 16 runoff.

But what operatives say remains unclear is whether Riser will face off in a runoff with one of three top Republicans — former Rep. Clyde Holloway, state Rep. Jay Morris or businessman Vance McAllister. Or, whether Monroe Mayor Jamie Mayo, a Democrat, will take the second-place spot and pave the way for Riser to coast into office in this strong Republican district in northeast Louisiana.

“There’s politics and then there’s Louisiana politics,” one Louisiana Republican operative said of the state’s jungle primary system. If no candidate receives 50 percent of the vote, the race goes to a runoff between the top two vote-getters, regardless of party.

Riser has been the front-runner in the contest since Republican Rep. Rodney Alexander announced in August he was leaving Congress to take a job as Louisiana secretary of Veterans Affairs in GOP Gov. Bobby Jindal’s administration.

He’s received the endorsements of House GOP leadership, including Majority Leader Eric Cantor, and many of the Republicans in the Louisiana delegation. Riser has also raised the most of all the candidates in the contest — $561,000 — and has Jindal’s former chief of staff, Timmy Teepell, as his top adviser in the race.

“As we look forward to Saturday, we’re very confident that our conservative message has resonated across the 5th District,” Riser Communications Director Ryan Cross said. “We’re confident that we’re the front-runner on Election Day and are looking forward to running a race focused on the issues.”

Republican strategists add that Holloway, a former member from 1987 to 1993 who now serves as a public service commissioner, has consistently polled in the second-place spot throughout the race.

If he made the runoff, Republicans said he’d likely try to tie Riser to Jindal, whose popularity has plummeted in the Pelican State.

When the election was called in August, Holloway accused Jindal and Alexander of working together to try to “rig” the election for Riser by giving him advanced knowledge of Alexander’s impending resignation, allowing Riser to get a running start. Jindal has denied the allegations.

Yet Republicans say Holloway could see his support slide on Election Day. He has been dogged in recent days by reports that he accepted campaign contributions from utility companies, after pledging not to do so.

Holloway’s slide in support could potentially pave the way for McAllister to capture that second-place spot.

A wealthy businessman who owns a pipeline company among other ventures, McAllister has positioned himself as the political outsider in the race. He would likely be the candidate with the most contrast to Riser in a runoff.

“We feel good about the race we have run,” McAllister spokesman Josh Robinson said. “It is obvious that people in the 5th District are tired of politics as usual. Vance is a regular guy running for Congress and people are responding favorably.”

And while the district voted for GOP presidential nominee Mitt Romney with 61 percent in 2012, there remains a third possibility that a Democrat can eke into a runoff if the second-tier Republicans carve up the conservative vote.

Operatives say Mayo, an African-American mayor of one of the district’s largest cities, would likely be the Democrat who could pull off that scenario.

However with other Democrats in the race, including state Reps. Marcus Hunter and Robert Johnson, the party would need to unite behind just one candidate for Mayo to be successful.

With a low turnout predicted for the contest, operatives say anything can happen on Saturday.

“Anybody that can successfully predict this special election should be a professional horse gamer,” one Republican said.