It’s normal for a sitting U.S. senator to endorse the re-election of a sitting governor of his own party. But in Louisiana, with U.S. Sen. David Vitter and Gov. Bobby Jindal, nothing is ever really normal.

When Vitter endorsed his fellow Republican for re-election this fall, the announcement immediately was greeted by comment on the fact that Jindal had not done the same when Vitter — tarred by scandal — faced re-election last year. Vitter survived. Now, the senator neatly calls Jindal “honest and competent,” and urges voters to back him.

That Jindal has no credible competition in the race so far is beside the point that Vitter was making: I am a loyal Republican, as you, governor, were not last year.

However, the comment on this little episode misses another and more significant line in Vitter’s endorsement, which was coupled with a plea for funds for Vitter’s state political committee, the Louisiana Committee for a Republican Majority.

Vitter credited his PAC for helping to “achieve majorities in both the state House and Senate. But we can go even further.”

That’s where things get interesting, with Vitter including an aside: “And with several RINOs, or Republicans-in-name-only, particularly in the state Senate, we need to.”

Does this mean Vitter will attempt a purge of Republicans who are insufficiently loyal to a litmus test designed by the state’s hard-line GOP senator? And who might be the targets?

Don’t expect any state senators to raise their hands and declare themselves RINOs anytime soon. Politicians always tend to act cautiously, as though they are permanently endangered species. And with Vitter on a RINO hunt, they might be.

All this suggests that, lacking credible Democratic challengers to many Republican incumbents in state offices this year, the fun part might be struggles within GOP ranks.