Remember those votes in the House and Senate where the Democrats rolled over and handed Shrub the unbelievably open-ended authorization (on false premises) to go to war?
I apologize for bringing yet another book into the mix, here, but I just finished reading Worse than Watergate, and it sheds a bit of light on what happened regarding that "open-ended authorization."

Here's what John Dean had to say:
But in granting this unprecedented authorization, Congress insisted that certain conditions be established as existing and that the president submit a formal determination, assuring the Congress that, in fact, these conditions were present. Specifically (and here I am summarizing the technical wording; the actual language may be found in the endnotes), Congress wanted a formal determination submitted to it either before using force or within forty-eight hours of having done so, stating that the president had found that (1) further diplomatic means alone would not resolve the "continuing thread" (meaning WMD) and (2) the military action was part of the overall response to terrorism, including dealing with those involved in "the terrorist attacks that occurred on September 11, 2001." In short, Congress insisted that there be evidence of two points that were the centerpiece of Bush's argument for the war.
 -- p. 148. (Emphasis his, typos mine).

So, while they did give Bush the power, they also stipulated some obligations that Bush must fill in order to use that power. Over the next couple of pages, Dean goes on to demonstrate how Bush did not, in fact, comply with those obligations.

This is not to say that the Dems (and others) didn't roll over when they shouldn't have, but it does demonstrate that they were hoodwinked by a rather unscrupulous administration.