In the latest round of polling in the David Vitter-Charlie Melancon U.S. Senate race, Vitter turned up with a huge 54-33 lead. And the incumbent Republican senator also turned up with a positive approval index – 25 percent said they strongly approve of Vitter, against only 17 percent strong disapproval.

So you’d figure it would be a safe thing for Vitter’s fellow Republican, Gov. Bobby Jindal, to endorse him for re-election, right? After all, few in Louisiana would expect any different.

But Jindal is opting not to endorse Vitter. Over the weekend, he dodged the question and told WDSU-TV in New Orleans that “Voters can make up their own minds.”

Jindal’s press secretary Melissa Sellers held out the possibility that the Governor might yet endorse Vitter before the campaign is over, though it’s difficult to imagine what’s going to change between now and Election Day that would induce Jindal to make a move. And the statement that the Governor doesn’t take sides in federal elections, which was offered as an explanation, doesn’t wash, either – Jindal endorsed Woody Jenkins when the latter ran for Congress in 2008.

The Louisiana Democrat Party was quick with their interpretation:

“The message from the governor is clear: he doesn’t want to be associated with Senator Vitter in any way,” Louisiana Democratic Party spokesperson Kevin Franck told RealClearPolitics. “His colleagues don’t want to work with him because he’s tainted in scandal and more interested in scoring political points than in getting things done.”

That’s obviously a politically self-serving and unserious explanation on Franck’s part, and he lacks credibility on this and a host of other issues based on previous – and contemporary – things he’s said. For example:

 “This race is more than just winnable…Charlie will win this race,” Franck said. “He’s exactly on target and right where we want to be coming out of Labor Day.”

From the standpoint of the state Republican Party, though, a Jindal snub of Vitter doesn’t look good.

Do Jindal and Vitter like each other a lot? Not particularly. Vitter is an unapologetic movement conservative willing to take controversial and uncompromising stands, and Jindal is more of a technocrat who does everything he can to keep the maximum amount of people happy. They occupy different sides of the Louisiana right as a result, and that makes them political rivals of a stripe. So is Jindal’s withholding of a Vitter endorsement a product of that rivalry or some other petty grievance? There isn’t any outward sign of that being the case, though it does bring to mind the rumor from a few months back which had Jindal jumping into the GOP primary against Vitter.

If Jindal isn’t withholding an endorsement because he doesn’t like Vitter, is he doing it out of an abundance of caution? Why would he do that? Vitter, for all his faults, is one of the state’s more popular elected officials and despite Franck’s zany boasting he’s a virtual lock to win.

The easy answer to that isn’t found among public opinion in Louisiana, but nationally. Nationally, Vitter is the guy who got caught up with the D.C. madam thing. For Jindal to endorse him means Jindal isn’t this wholesome non-white conservative Republican who talks a mile a minute and does a nice job governing a backwater state in flyover territory; the endorsement means Jindal throws his lot in with whoremongers and such. And that might be a blemish on a sparkling record for a national Republican figure.

Why would Jindal care, though? He’s not a national figure, he’s Louisiana’s governor. He’s got a re-election campaign coming up next year that he swears he’s going to pursue. One would think an alliance with Vitter would do more good than harm inside the state.

Does this indicate Jindal is prepping the ground for a presidential run in 2012? Perhaps it’s more an indication that other Republicans do what they can to help Jindal, and in return Jindal does what he can to help Jindal.

Either way, withholding an endorsement of Vitter isn’t likely to play well with the 55-60 percent of the electorate (at least) which is likely to support the Senator’s re-election bid. It would have been a lot less controversial for the Governor to have done the endorsement quietly and gotten it over with.