A Weaker Hand Than People Realize?

Nyhan explains why Obama couldn't get what he wanted on the Bush tax cuts. Bernstein is in neighboring territory:

The truth is that there are a lot of people who just don't accept that the President of the United States can want something, fight for it, fight effectively and correctly, and still not get it.  If it doesn't happen, it must have been -- in Obama's words -- a "betrayal."  Those people are wrong.

And yet it's awful hard to believe that calling people out on it -- his allies, the activists within the Democratic party --  will do him any good.