An additional thought on the Lieberman story below. It is apparent that Lieberman is calling in a lot of chits in order to defend against Lamont. The thing about chits is that, once they are called, they can't be called again. This means that, in order to defend himself, Lieberman has to spend a lot of political capital that he will have to work afterward to rebuild.
In other words, even if Lieberman succeeds in holding off Lamont, all those people he called up asking him to help him out will now have his number.
This is why contested primaries are a good thing. They force incumbents to mess it up. It keeps them from growing stale and entrenched. It's the equivalent of shuffling the deck in order to keep the game fresh. Even if the incumbent wins, they will have to work that much harder afterward to rebuild the kind of political capital they needed to fend off the challenge.
Lieberman will have to start acting more like a Democrat. Otherwise, the next time, he will have even fewer chits to call in.