Jonathan Bernstein has a hard time drawing conclusions:
I'd separate the effects (likely some 1-4 fewer GOP Senators taking office in January) from the explanations of what exactly has happened. Is this, as Ed Kilgore thinks, "the final victory in a Fifty Year War waged by the conservative movement for control of the Republican Party"? Maybe (and I like Kilgore's post in general; I think he's right about Tea Partyism), but I'm not confident about that. Another way to look at it is in terms not of ideological differences, but in terms of a fight within the conservative movement between purists and professionals over best tactics. Or perhaps we're seeing proxy skirmishes in the 2012 presidential nomination process (DeMint? Yup, he's a player). Or perhaps it's a handful of local situations (purist candidates defeating weak alternatives in Colorado and Nevada, a local personal feud in Alaska, a strong candidate possibly miscast as a purist in Florida, and then in Delaware a real honest-to-goodness moderate who, unlike almost all of the others, really was out of step with his party on the issues.
The Dish 