Certainly the Iraq debacle and the weak economy should have given them backbone earlier.
But it didn't turn into a "debacle," by bourgeois standards, until rather recently. It was only when it did, and when Bush started stepping on some important toes (e.g., those in Langley) that things started turning. Also, the economic problem could be dismissed as just a slow recovery. The longer the labor market has refused to recover, the worse the political atmosphere.
And it's taken about 2 years for 9/11 to wear off. It's not really all that surprising.
Doug