If it's that simple...
Then why aren't the Democrats just standing up in Congress and cutting the war off at the knees?
What are they scared of? Do they know something you don't?
Frank has a good point. You could put any unknown factor in next to Bush and get that kind of a result.
Would be interesting to see what would happen if Murtha was specifically named in such questions.
Incidentally, Bush's approval rating is 36 to 62 (approval/disapproval.)
Congress is currently holding out at 41 to 54.