I've just watched the whole conference, though, and I thought the whole was the best performance of his presidency...Suffice to say that I came away confident that he will battle the Republicans at least as effectively as Clinton did, and that his communication skills are out of storage. This encounter was antidote to his post-election remission. Within the context of the whole - what the Republicans stand for, what he and the Democrats stand for, what they've accomplished in the last two years -- the attack on "purity" was appropriate. What's missing in the news reports is that it was part and parcel of his defense of the really (on long view) extraordinary accomplishments of the 111th Congress -- a defense that was sorely missing in his post-election performances.One of the things that I find frustrating as an analyst is how often people say that the president (or Congress, or a candidate) should say this or that -- when in fact, the president has been saying it for months, and no one notices. Now, it's not always clear whose fault that is -- certainly, Barack Obama should have known that once he started attacking liberal purists that liberals wouldn't notice anything else he said. But if there's something that you think your party should be saying, odds are they already are. Anyway, read the whole thing -- Sprung is as good a careful reader of Obama's rhetoric as you're going to find.
Meanwhile, on the last (purist-bashing) answer, I think Adam Serwer is probably correct about the mindset of the president. I'll extend what I said yesterday: no matter how justified the president's annoyance with liberal critics might be, he has no business voicing his frustration with them unless there's some particular goal in mind, and I can't think of one. He should have known going in that liberals were going to be disappointed by whatever he produced (just as liberals were disappointed with FDR, JFK, LBJ, and WJC when they were enacting some, but not all, liberal goals).
I'd also say that this White House has done an unusually poor job of finding low-cost and/or symbolic ways of making liberals happy. And that's true even if the people in question tend to be purists who are oversensitive to minor slights. Liberals spent a lot of time and effort complaining about George W. Bush's dog whistles to Christian conservatives, but it helped to keep people happy that Bush usually didn't have the votes to pay off in substantive ways. Sure, those things only matter on the margins, but that doesn't mean the White House shouldn't do it.