They waited until they lost the House before trying it out, though. And it's still all very arcane.
Update: Here's a simpler breakdown of what happened:
What Senate Democrats did is that they voted to overrule the Senate parliamentarian.
By rule and by custom, both parties abide by the decisions of the parliamentarian. But the rule that establishes that basic guideline was originally approved by a simply majority vote, so it can be changed by a simply majority vote. That's what Senate Democrats last night.
Senate tradition is that you don't tweak the rules on a piecemeal basis like that. Now that Democrats have done so -- even though it involved just this one bill -- it sets a precedent for a future majority (i.e., a Republican majority) to do so again on matters of greater consequence.
The mechanism Democrats used -- voting to change the Senate rule -- is the same mechanism that could be used to undermine the power of the filibuster and other privileges enjoyed by the minority in the Senate.
Did Democrats play dirty pool here? In one sense, yes. This was a break with custom and tradition. It was a raw power play.
But if you think Senate rules are anti-democratic -- or that custom and tradition are merely a nice way of saying byzantine and corrupt -- then you might see this as the first step toward bringing the Senate into the 21st century.
I tend to be sympathetic to the latter point of view, but my sense here is that Senate Democrats, with a few exceptions, aren't really prepared to tackle fundamental Senate reform. So rather than being the first step toward reform, Reid's move last night merely weakens Senate traditions, creates greater uncertainty and unpredictability in the legislative process, and doesn't offer much promise of a comprehensive and better way of running the Senate.
That Reid's power play comes right as Senate Democrats are on the brink of finding themselves in the minority again makes the move more baffling.
To me, the short term advantage or disadvantage for the Dems is irrelevant. The Senate filibuster rules are anti-democratic and, no matter how lamely the Dems stumbled into this or whether it's the Democrats or Republicans who will take advantage of it first is irrelevant. The Senate should be a majority-ruled institution except for veto overrides and other special cases as specified in the Constitution (constitutional amendments, treaty ratifications), and this action moves us back in that direction.
That said, the question of "why now?" is certainly fair. Why not for the stimulus, the public option, etc., etc.?
Oh by the way, we're back from Vegas, and yes, i'm already back to obsessing over politics.