Just ask them this one question.
If congress wasn't an issue, how much longer would Bush need to win this war?
You will invariably get the meme about Freedumb not being free and that it takes time to build a democracy.
They may even try to spin it that the Democrats are forcing the U.S. to surrender by holding them to a timetable to withdraw. They may even try to call you a monster for allowing thousands of Iraqis to die if the U.S. pulls out. (Not that it isn't already happening with us there.)
Just keep asking the question, "How long would Bush need to win this war?" They will sputter and squeak, but they will avoid the question like an army recruiting station.
The truth is, that despite their partisanship, they know this war is unwinnable. They are the ones who have no answer or plan.
Eventually, they will need a scapegoat to blame the loss on like this genius does here.
After we withdraw, all they will have left is the Scooby Doo defense, "We could have won if it weren't for you meddling hippies!"
Go get 'em! Keep up the great work you are doing on DK.