You've got it wrong. You're missing a critical point.
If the Democrats don't fund the war, it will end.
Bush will make fake moves, but if he lets soldiers die because there's no money, it will be obvious that he's the one who's killing them, just to have his way.
The public has learned to see Bush as a spoiled and vengeful stubborn jerk, and they will accept that he would kill their sons and daughters to make a point.
Then the Dems solicit money online to put plenty of ads saying that Bush is killing our troops just to be stubborn.
The public will see it that way. If you don't know that, you shouldn't be in politics.
In a public relations war, the Dems will win because people want out of the war, and turning on Bush, and the Republicans will be psychologically easy.
update: Kagro X stole my story. Or you could say, "rescued" it. I don't mind. He wrote a lot of words, but the truth is simple. No guts, no glory, no 2008 election win.