Basically, anti-war Democrats think that their statements and policy proposals are a response to an impossible situation in Iraq. They have it backward. Their statements and policy proposals are a main reason why the situation in Iraq is so dire. Like it or not, the enemy is counting on them — it is trying to manipulate American public opinion, because it can't win on the battlefield. Their goal is an ignominious American retreat. It cannot be in our interest to comply.
If you want to make an argument that attitudes on the homefront are detrimental to the war effort, you can do so while perhaps retaining an ounce of credibility, but to argue that statements by Democrats are the main reason that Iraq is in such a bad state is just plain idiotic, ahistorical and dishonest.