This is a terrific post today by Jonah Goldberg of NRO:
"[O]ne plausible theory as to why the Democratic party is having some of its problems these days is that they misread their pre-election unity. I think this is understandable. Lots of polls suggested that America was becoming more liberal under Bush (at least on a bunch of issues). The differences between centrist and left-wing Democrats seemed trivial. Barack Obama won handily without ever tacking back to the center in the general election. In short, those eager to find evidence that the country was poised to lurch leftward had lots to go on. But perhaps that had more to do with the fact that country was (again understandably) fed up with the Republican party. The Democratic party's leaders are a lot more liberal than their voters (the dynamic is even more true when it comes to committee chairs who are to the left of the average Democratic congressmen). The Democrats came into power in 2008 thinking they had a huge mandate for liberalism, when they really had a huge mandate for competence (for want of a better word). Obama and his coterie misunderstood this."
Be sure to read it all.