This whole article exists because Greeley has heard tell of a planned change which, he fears, Bush or the "Neocons" or someone might be able to paint as success/victory. He therefore wrote this article to help shore up the new (impossible) definition of success/victory in warfare to make sure that the United States still can't do it. He also wants to remind Democrats in Congress to do their part ("Democrats in Congress will tear it to shreds") and continue to stick to the definition of success/victory according to which the United States can't possibly do it. (Shoring up this definition requires constant effort and maintenance)
This is all a rhetorical battle at this point. In reality, the United States actually won "The Iraq War" (tm/2003) in 2003. What's going on now is merely a battle over the verbal definition of winning/success. And the lefty intelligentsia has basically won that battle because even most conservatives don't realize we won "The Iraq War".
So, like I said, Greeley is right.
The idea is to try to avoid the WWII aftermath when we won the war but lost the peace.