As Matt Stoller notes there's a remarkable effort under way to excise the debate over the wisdom of the Iraq War from the Democratic primary. Certainly, there was more than that one issue in play. Nevertheless, it's essentially unprecedented for a challenger to unseat an establishment figure as well-entrenched as Clinton, and it's very clear to me that it was the war issue that gave Obama a plausible opening to mount a challenge.
The war alone didn't -- and couldn't have -- put Obama over the top, but it's what create a base of discontent with the "inevitable" Clinton and what allowed an alternative to get a hearing. And that's an important development, a world in which Clinton became the nominee would be a world in which there was no conceivable political upside to opposing any war ever.
U.S. Air Force photo by Airman 1st Class Matthew Plew