Aww. You should have waited with the answers.
I got a few wrong.;^)
My opinion on what changed AFTER those two votes - the 2002 midterm elections, held less than a month after the Joint Resolution was approved in October of 2002. People forget that the 29-21 Democrat vote was in a Senate led by the DEMOCRATS! (thanks to Jumpin' Jim)
Why in the bloody hell would people who have been on the wrong side of national security for years, in a party known for the same, suddenly be gung-ho hawks? The prospect of electoral success. The Republicans had run the House since 1994, had the Senate in the 2000 election but lost it when Jeffords jumped, regained the White House (in what the Left still believes was a stolen election)...
A year after 9/11, when the outrage and death was still fresh on America's mind, there was no way these chicken****s were going to appear weak on National Security and Foreign Policy.
Well, a month after the AUMF vote, the Democrats did not regain the House - they wouldn't, for another four years - AND lost the Senate, which they wouldn't regain until four years later. It was amazing to me, how quickly they reverted to form. I wasn't following politics that closely, before mid to late 2003. I remember all the stories about Iraq being a quagmire, and I remember thinking to myself,
"How can Iraq be a quagmire? The war hasn't even started yet?" And the same people who were calling it a quagmire, were the ones who had voted for the AUMF a few months prior.
My $0.02.