My cynical view of this is that these rats, and likely a few more have seen that a large portion of the Rat voting base has been relocated and will not be returning soon, thus giving the GOP a strong chance at picking up the majorities. And the Rats in LA being about the most corrupt in the nation, their desire to remain in the majority, regardless of the letter after their name is what is driving their party changing.
As a Republican in Louisiana, I cannot wait to vote Mary Landrieu's arse out of the Senate next year. Same with Blanco as governor. It was the Demonrats' voting bloc in New Orleans (now scattered, thankfully) that got them in office to begin with.
You got it. They are not exactly subtle.