One of the surest axioms of politics-watching is that folks who say they're going to win not by getting a bigger slice of the pie but by expanding it are full of it. That sounds a little cynical. But you would put together a very good record of prognostication by assuming it's always true. And that's one thing that stands out to me about last night on the Democratic side. As Eric Kleefeld points out here, among returning caucus-goers, Edwards won last night with 30%. But 57% of caucus-goers were first-timers. And Obama won those newcomers decisively -- 41% to Hillary's 29% and Edwards at 18%.

I don't think it's fair to credit all the expansion of the Democratic electorate to Obama. There are a number of factors, several of which are pluses for the Democrats in general. But he won them resoundingly.

And clearly there was no way to peg this outcome if you figured by looking at the makeup of previous caucuses.

Another point that needs saying. There was a lot of talk going into last night that Obama was going to overwhelm the caucuses by bringing in tons of independents. That didn't happen. As a percentage of caucus-goers independents made up almost exactly the same percentage as they did in 2004.

(ed.note: A lot of readers have written in about this last paragraph. So perhaps it's unclear. Whoever brought them, there were clearly about twice the number of independents caucusing with the Democrats last night as compared to four years ago. My point, however, was whether they would 'overwhelm' the caucuses in the sense of change their partisan complexion. And that clearly didn't happen since the breakdown of Dems and Independents remained the same.)