From the post-State of the Union discussion on the Charlie Rose Show (1/25/11):
CHARLIE ROSE: With respect to his base, where are they tonight? They listened to him move to the center–
JOHN SUNUNU: On the Upper West Side.
JOHN HEILEMANN: Drinking heavily on the Upper West Side.
The discussion went on to explain how the progressive base either really likes Obama, or won't have anyone else to vote for so it won't matter what they think. Such discussions are a lot easier to have when you don't invite any actual progressives who might disagree with the Upper West side jokes.