Politicians endorse for all kinds of reasons. Sometimes it's obligation. Sometimes it's genuine affection, or like-mindedness. Sometimes it's actual alarm about the other choice.

1) Anyone who watched the gubernatorial primary knows what Lt. Gov. Jay Dardenne thinks of U.S. Sen. David Vitter, who spent much of the primary season grossly mischaracterizing his moderate and generally respected foe's past legislative votes and ethics.

And since Dardenne finished fourth in the primary, television viewers have been reminded of that nightly, via a masterful commercial produced by the Gumbo PAC, financed by the Democratic Governors Association, and built entirely on the testimony of Vitter's vanquished Republican foes, both Dardenne and third place primary candidate Public Service Commissioner Scott Angelle. It features a choice clip of Dardenne describing Vitter as "ineffective," "vicious," and "lying," and arguing that Vitter's prostitution scandal is a "stain" on Louisiana.

So, in a sense, Dardenne's big-time plug for Democratis state Rep. John Bel Edwards comes off as personal.

2) Still, it would be a mistake to dismiss Dardenne's move as sour grapes.

While they come from different parties, the two showed a clear mutual respect over the course of the campaign, and not just over their conciliatory political philosophies. It came off as personal,too; you got the sense that each saw the other as an honest broker and a good person. Indeed, in accepting the endorsement, Edwards said he values not only Dardenne's support but also his advice.

And if rumors are true and the plan is for Dardenne to join an Edwards administration, the endorsement carries an extra significance. Not only does Dardenne bolster Edwards' main argument that, in contrast to Vitter, he's the candidate with integrity. It also goes a long way toward inoculating Edwards against Vitter's go-to charge, that he's nothing more than an Obama liberal. It sends the message that Edwards would govern from the center and seek to bring people together. Not that he has a choice, given the Legislature's Republican leanings, but it's still a vital message for him to communicate if he hopes to go all the way on Nov. 21.

Louisiana doesn't have formal tickets, but a partnership between Edwards and Dardenne is perhaps the next best thing. And unlike most endorsements, this one packs quite a punch.