There were no WMD's. That was a blow to our reasoning for going in there. Now the voters are very unhappy with our young men and women dying over there and no end in sight.
Americans do not like war. They want it over with with the least amount of casualites and damage. The people rule in America and what needs to happen in Iraq is not more killing - but working with the Iraqis realistically - with respect toward who they are - with the goal of leaving them with a system that will not be a breeding ground for terrorists and is a better place than the one we invaded.
What color is the sky in your world? Iraq is not going to turn into Sweden. Its future is one of civil war, genocide and ethnic cleansing of the Sunni population.
People are fed up with seeing American soldiers in a 'politically correct' war. We see the neccessity for war at times and don't shrink from it. But, pc wars are wasteful of lives and money.