Louisiana gubernatorial candidate Sen. David Vitter (R-La.) speaks to reporters after a Nov. 16 debate against Democratic candidate John Bel Edwards in Baton Rouge, La. (Gerald Herbert/AP)

Charges and countercharges involving thugs, terrorists, prostitutes and spies have dominated the raucous final stretch of a Louisiana governor’s race that was, until recently, expected to be an easy victory for Republican Sen. David Vitter.

The prostitutes and spies have been Vitter’s main undoing: His opponents have run repeated ads about his involvement in the “D.C. Madam” call-girl scandal, and his campaign was caught spying on one of his rival’s main donors last month.

That’s where the prison “thugs” and terrorists come in. In a last minute appeal before Saturday’s election, Vitter is hoping that portraying his Democratic opponent, John Bel Edwards, as soft on crime and Syrian terrorists will help him overcome what polls show is a sizable deficit.

At stake for Vitter is not just the governor’s race but, possibly, his political future: A decisive loss could imperil his chances of winning a third term in the Senate next year.

“Voters might just say they’re done with him,” said Roy Fletcher, a longtime Louisiana political consultant. “Maybe there will be blood in the water.”

Sen. David Vitter (R-La.) appears in a video ad with "Duck Dynasty" star Willie Robertson. Vitter is competing against Louisiana Democrat John Bel Edwards for the state's open governor's seat. (David Vitter)

Vitter has won seven elections in a row and has shown, throughout his career, an ability to do what it takes to win — both for him and his allies. Last year, for instance, he pushed aside other would-be contenders to guide then-Rep. Bill Cassidy to a ­12-point victory to seize Mary Landrieu’s seat in the U.S. Senate. With her defeat, no Democrat currently holds statewide office in Louisiana.

In the governor’s race, Vitter has tried to cast Edwards, a Democratic state representative with a military background, as a “liberal” clone of President Obama. In one TV ad, Vitter accuses the Democratic candidate of favoring the release of 5,500 “thugs” from Louisiana prisons.

Edwards countered with an ad in which a popular sheriff said the attacks on the Democrat “are not only false, they are irresponsible.” The state sheriffs association is backing Edwards.

Since last week’s Islamic State attacks in Paris, Vitter has played on fears that terrorists from Syria posing as refugees might be heading to Louisiana — 14 Syrian refugees have been resettled here — and has accused Edwards of not taking a tough stance against them.

Edwards responded with a TV ad in which he said he wants no more Syrian refugees to come to Louisiana. “It comes as no surprise that David Vitter is distorting the facts and trying to use this tragedy to save his desperate campaign,” Edwards says in the ad.

On Tuesday, conservative Web sites quoted Vitter saying that one of the 14 Syrian refugees in Louisiana was missing and thought to be on his way to Washington. The Vitter campaign began making robo-calls to voters warning that hordes of Syrians would soon be invading the United States, thanks to Obama.

Gumbo PAC released an ad criticizing Louisiana gubernatorial candidate David Vitter (R) for his stance on accepting more Syrian refugees. (GumboPAC/YouTube)

The superintendent of the Louisiana State Police, Mike Edmonson, ultimately clarified the situation. “There is no missing Syrian,” he said in an interview, adding that the man in question successfully applied to resettle with his family in Washington.

“It’s the last breath of a dying campaign,” Edwards said in an interview.

The overriding issue throughout the race has been the resurrection of Vitter’s 2007 admission that he had committed a “very serious sin” a half-dozen years earlier in connection with the “D.C. Madam” call-girl service.

Vitter thought he had put the scandal behind him when voters reelected him overwhelmingly to the Senate in 2010, but a Baton Rouge law firm spent nearly $2 million on attack ads reminding voters of it. The two Republicans who lost in the primary chimed in, saying that his conduct showed Vitter is untrustworthy and unfit for office.

Also dragging down Vitter has been the political demise of Louisiana’s once-wunderkind governor, Bobby Jindal, who suspended his long-shot GOP presidential campaign Tuesday.

With Jindal’s approval rating down to 20 percent in a recent statewide poll, Edwards has repeatedly said that a victory by Vitter would mean a continuation of Jindal’s policies.

Ironically, the two Republicans can’t stand each other. Vitter didn’t seek Jindal’s endorsement, and Jindal refused to disclose which candidate he backed when he voted early.

Late last month, Vitter faced a string of unfavorable news reports after he was caught spying. A sleuth hired by his campaign was discovered secretly videotaping a major Edwards donor at a suburban New Orleans coffee shop. Once he was spotted, he left the coffee shop and broke into a run. He was arrested while hiding behind an air-conditioning unit at a nearby home and charged with criminal mischief, a misdemeanor.

Edwards, 49, who comes from a long line of sheriffs in rural Tangipahoa Parish, graduated from West Point and commanded paratroopers in the 82nd Airborne Division. He became a small-town lawyer and has spent the past eight years in the state House, where he has led the opposition to Jindal. Edwards has a 100 percent voting record from Louisiana Right to Life and sports an A grade from the National Rifle Association.

Edwards has kept the runoff election squarely focused on Vitter’s character, contrasting it with his own.

“I will always be honest with you,” he told a roomful of supporters Wednesday in the bayou town of Houma. “I will never embarrass you.”

During a debate between the two men Monday that turned into a verbal brawl, Edwards said, “I don’t try to give 100 percent to anyone other than my wife,” and added that Vitter ought to emulate him.

Vitter’s wife, Wendy, has stood by him since his veiled apology in 2007. But it’s only recently that her husband has felt he had to address the issue more directly with voters.

“Fifteen years ago, I faced my darkest day in life when I had to look my kids in the eye and tell them how badly I’d failed my family,” Vitter said during his closing statement Monday night. “What they gave me in return was the best day of my life, when they and Wendy offered complete love and forgiveness. And that was absolutely the single best day of my life and the most powerful motivator I had for the rest of my life.”