Never happen. Not from the real "lefties" (as opposed to merely misguided or soft-headed "liberals"). Not, in any case, with a level of conviction that will convince anyone. To make that argument would implicity endorse the basic justice of the liberation of Iraq, and this the left will never acknowledge. They will always "blame America first".
I think you miss the point. The Left is nothing but contrarian. Whatever the Republicans want to do, the Left will oppose. To do otherwise cedes the notion that the Right might have some right to govern as well.