Mr. Petraeus goes to Washington

As Shaley Shale, our prophet and guide, mentioned in class today General Petraeus is briefing congress on the fragile state of affairs in Iraq currently. The general believes that after the 20k troop surge ends, troop levels should stay level in Iraq until further notice. Chairman Sen. Carl Levin (D) of Michigan, voiced the trite statement of discontent with the current situation; his sentiment will most likely be repeated by fellow democrats and defecting republicans. It's intersting to see the distance that many former supporters are developing now that the war is unpopular accross the board. My question is, why didn't more Congressman and Senators realize that this would happen in the first place, that they would ultimately need to back down from their support? We talk about sophisticated and strategic voting, where was that in the vote to go to Iraq? Was it done in the votes leading up to it, such as the mentioned Kerry statement: I voted against it before I voted for it (?) Many questions over such a thing I have...