Governor John Bel Edwards greets people after a press conference at Orleans Justice Center in New Orleans, Thursday, Oct. 18, 2018. Governor Edwards announced Justice Reinvestment grants are being distributed to Orleans, Jefferson and St. Tammany parishes.

There have always been two competing theories as to why Democrat John Bel Edwards was able to win the 2015 governor’s race so handily, Louisiana’s Republican leanings notwithstanding.

One is that the election was an aberration.

Then-U.S. Sen. David Vitter, Edwards’ runoff opponent, had never before lost an election and was easily the state’s dominant Republican. Yet somehow he was fatally damaged — by his old prostitution scandal, his take-no-prisoners tactics (which he first aimed at Republican primary rivals, to ugly effect), similarities to unpopular outgoing Gov. Bobby Jindal, or some combination of these factors. Edwards skillfully exploited Vitter’s weaknesses, and slid in.

According to this world view, which I’ve heard from many a politically active Republican, 2019 is bound to be a correction, a return to normal order in which Louisiana’s electoral majority once again sides with the GOP.

The second, opposing theory is that gubernatorial races are unique.

Yes, Louisiana voters tilt Republican in federal races such as next month’s congressional midterms, which are, as always, deeply partisan and heavily focused on the president and legislative control. They also tend to go with Republicans in down-ballot races such as the special election for secretary of state, which is also on the November ballot.

But for governor, many voters approach their vote differently, this theory goes.

Maybe they care less about partisanship in this office and more about services that are close to home such as higher education, local hospitals and services for people with disabilities. Or maybe they simply gravitate toward the center.

This isn’t a phenomenon that’s unique to Louisiana; among the most popular governors nationally are a pair of pragmatically minded Republicans who lead Democratic states, Massachusetts’ Charlie Baker and Maryland’s Larry Hogan. Jindal, who enacted the sort of low-tax, low-spending policies he hoped would take him all the way to the White House, wound up among the least popular governors nationally — as did former Kansas Gov. Sam Brownback, another austerity-minded leader of a conservative state who saw his poll numbers plummet when he put his philosophy into action.

Or maybe it’s just more personal. Voters sent Vitter back to Washington after they learned that his phone number was in the records of a prostitution ring, in a campaign in which he hammered his opposition to President Barack Obama. But without the president as a factor, he was a much tougher sell for governor — particularly when compared to a sincere-seeming military man who ran on the idea of honor. Also working in Edwards’ favor was his conservatism on certain hot-button social issues, specifically guns and abortion, which he believes gave potentially suspicious voters permission to give him a chance.

Grace Notes: Louisiana finally has a governor's race -- or at least the beginnings of one

That doesn’t mean he’ll have an easy time getting reelected, particularly if U.S. Sen. John Kennedy jumps in. Kennedy now says he’ll decide by Dec. 1, and is already hinting at a classic R-versus-D approach to a campaign.

“Medicaid spending is almost half of our entire budget with little or no effort to control costs,” he said in a statement. “The state’s criminal release program ignores public safety. And our governor continues to believe we are just one tax increase away from prosperity.”

Never mind that Medicaid expansion under the Affordable Care Act now serves nearly 500,000 Louisianans largely on the federal dime, and that criminal justice reform has substantial Republican support, and that both were issues that Edwards specifically promised to tackle before voters chose him the first time. And never mind that Edwards would not have been able to raise taxes without the grudging support of the Republican majority Legislature.

One other Republican, Baton Rouge businessman Eddie Rispone, has already declared his candidacy. Still waiting in the wings is U.S. Rep. Ralph Abraham. He’s running for reelection to Congress in November, but his biographical ads, which are airing in the large media markets that touch his mostly rural district, could also offer a nice introduction for an upcoming statewide race.

Whoever emerges as Edwards’ main challenger is likely to subscribe to the theory that Louisiana is a Republican state by default and that voters who strayed three years ago are ready to come home.

Edwards’ theory of the campaign, of course, is that they're already there. 

Follow Stephanie Grace on Twitter, @stephgracela.