Lt. Gov. Jay Dardenne speaks during the Louisiana gubernatorial debate held at the University of Louisiana at Lafayette on Oct. 14. (Paul Kieu/the Daily Advertiser via AP)

Jay Dardenne, a defeated candidate for governor of Louisiana, has endorsed a Democratic rival for the job over fellow Republican David Vitter. In a news conference this morning at Louisiana State University, Dardenne called Democrat John Bel Edwards a "pro-life, pro-gun" candidate, as apt for the job as Vitter was unthinkable.

Edwards "knows that fear, intimidation and vindictiveness are the enemies of putting Louisiana forward," Dardenne, the state's outgoing lieutenant governor, said. "The Republican brand has been damaged by the failed leadership of Bobby Jindal. A David Vitter governorship would further damage that brand."

Dardenne's move drew a vituperative response from the national and state Republican parties. "Today, Jay Dardenne became the Nick Saban of Louisiana politics," said Roger Villere, chairman of the Louisiana Republican Party, referring to the former LSU coach who now guides a rival team at the University of Alabama. "It is sad that Jay allowed his personal feelings to cause him to betray his party and state."

Reince Priebus, chairman of the Republican National Committee, cast Dardenne's move as a betrayal of a surging GOP, which registered a surprise victory this week in Kentucky's gubernatorial race. "The party's efforts have been tireless and effective and it would be extremely unfortunate to undo some of that hard work," Priebus wrote. "We do not think you would personally endorse the likes of Barack Obama or Hillary Clinton but supporting Mr. Edwards is one in [sic] the same."

That echoed the national Republican Party's message in Louisiana, that a vote for the moderate Edwards was a de facto endorsement of the unpopular presdent. That message was successful in Kentucky, where Democratic nominee Jack Conway got no traction from joining a lawsuit against the Obama administration's environmental regulations.

In Louisiana, the message has yet to sink in. Over the past week, three statewide polls have found Edwards further ahead of Vitter than Conway ever was in his battle against Gov.-elect Matt Bevin. Outgoing Gov. Bobby Jindal (R-La.), whose approval ratings have sagged in tandem with state tax revenue, has declined to endorse Vitter.

That has roots in a long-running feud between the two Rhodes scholars-turned-GOP politicians; it is enabled by the damage done to Vitter after a 2007 report in Hustler magazine said it found his name among the clients of a D.C. prostitution service. Dardenne's anger toward Vitter runs just as deep; the former candidate is convinced that Vitter had a role in rumors that dogged his campaign, as the senator attempted to clear the field for this gubernatorial race.

To win, Edwards must break a pattern of Republican success in Louisiana, a state that gave just 40.6 percent of the vote to the 2012 Obama-Biden ticket. Between them, Edwards and Dardenne racked up a majority in last month's jungle primary, and Edwards has attempted to portray his campaign as a fusion of Democrats and Republicans vs. the scandal-plagued Vitter. In a new ad, he responds to Vitter's attacks on his views about criminal justice reform by rolling out Republican and Democratic sheriffs who loudly agree with him.

Republicans, led by Priebus, hope that Dardenne's endorsement can be turned into a problem for Edwards.

"The vibe I’m getting from the Vitter camp is they actually think this helps them," wrote Scott McKay, publisher of the Louisiana conservative blog the Hayride. "Among the insider crowd I talked to, everybody seems to think that Dardenne extracted the Commissioner of Administration job as a concession from Edwards." McCay's theory was illustrated by an image of Ephialtes, the deformed betrayer of the Spartan army, from the book and film "300."