Why Krugman?

You have to ask why would Obama throw Krugman under a bus?  Why? Obama seems to be serious about policy.  He is progressive on many issues.  Presumably, too, a lot of his voters read Krugman and share his views.  

And it's the Democratic primary.  Obama's not going to get primary voters to switch from Edwards or Clinton by knifing Krugman.  It didn't help rally the liberal blogosphere.

So what did it do? Who was the audience for the bizarre display of trying to stomp a progressive icon for making a reasoned policy critique of the candidate's plan?

Perhaps it was the Washington establishment?  The MSM establishment?  Both?  After all, Krugman is hated in the MSM.  Just hated.  He's joked about it here.  And the National Review confirmed it here.

Perhaps, just perhaps, was Obama signalling to the powers that be that he is one of them?  And that they can safely embrace him.  That he's electable. Was this his Sister Souljah moment?

Why do you think he did it?

And yes, I'm still undecided.  But I'm leaning against Obama in the primary.