I'll start with his last point. In Nate's view, Olympia Snowe was surprisingly ineffective in developing her "trigger" compromise. I don't know...does Snowe have a long and successful history of being a creative and innovative politician? I'm not convinced that's the case. What was more important here is that, compared to the stimulus situation, the numbers have changed dramatically. In the spring, there were 58 Democrats in the Senate, and Snowe was joined by two other Republicans. Their votes were needed (well, at least two of the three were needed). Now, there are 60 Democrats, and Snowe appears to have bring only her own vote (since Collins appears to be siding with the rejectionists, and Specter is no longer a moderate Republican). In other words the best explanation here isn't that Snowe "didn't do her homework on triggers;" it's that her bargaining position has deteriorated significantly as the numbers changed.
Now, his second point is that the White House didn't do much for the public option, at least publicly. I don't know how much of a surprise that is, but this one fails the other half of the test -- Nate doesn't actually believe that WH silence helped the public option in any important way.
This leaves three points, which I think boil down to one main idea. Let's see the points, in Nate's words:
The first surprise is that Reid is showing some backbone.There's really only one surprise here: Nate is surprised that the Democrats didn't turn tail and run at the first sign of resistance. Nate believed -- lots of liberals believed, in a narrative that goes back at least to the Iraq vote in 2002 -- that the Democrats are a bunch of 'fraidy-cats. A few nuts at a few town hall meetings were sure to make the Dems freak out and give up. The prospects of a close vote were sure to make the Dems freak out and give up. Surely, the opposition of big lobbyists would make the Dems turn away from the liberals. Everyone knows that Democrats may mouth liberal platitudes during campaign season, but they're really just in hock to big corporate interest groups.
The third surprise is the way that Democrats regrouped after the turmoil of August.
The fourth surprise, less important than the first three, is that the usually very footsure insurance lobby undermined its credibility by putting out the wrong study at the wrong time, giving a gift to Democrats by making it easier for centrist Senators to distance themselves from them.
The best explanation is all of this has nothing to do with backbone; it has to do with numbers. In 2002, Democrats were in the minority, and didn't have the votes to win on Iraq. In 2007, Democrats had majorities in Congress...but not the White House, and so they had only limited ability to affect policy. In early 2009, Democrats picked up the White House and reached 58 seats in the Senate, leaving them in pretty good shape but still vulnerable to unified Republican filibusters.
And now the Democrats have reached 60 votes in the Senate, and it has consequences. That's not about will, determination, or spine; it's about numbers. To the extent that Democrats have 60 votes but not 60 liberal votes, the ability to do what liberals want will be compromised, but again it's the numbers (both in terms of party and in terms of preferences of Senators) that really matters. Those sorts of explanations aren't, perhaps, as dramatic, but they do have the virtue of being more accurate.