In the first place, I'm afraid you underestimate how mad our madmen are. Long and bloody and a big mess wouldn't bother them a bit. As far as they are concerned it has a huge upside -- it would get them immediately into surrounding countries.
-Yes, but if they start to get heavy losses and become even more agressive, -this will led to further losses, increased expenses and progressive -weakening of economy, which could led to an weakened US.
In the second place, you are wrong that they couldn't be defeated if they win the war cleanly. His father lost the election after a cleaner victory than this can ever be. And most importantly, they not only can lose the peace, they are going to lose the peace. Which will be more important than winning the war -- if we make it so.
-The Republicans lose, of course, but then US hegemony became stronger -and the US leadership became more and more inclined to interventionism -in the 90´s, so Bush´s defeat ddidn´t help too much. Actually the unhappy -coincidence of USSR disintegration and a easy US victory in Iraq led us -to the absolute military hegemony the USA enjoys now. I don´t want to -have a democrat president elected. I want to have a weakened USA, both -in economics and military terms, not that I think other powers will -be much better, but a better balance of power is a good thing itself.
It's the political battle that is decisive. The war won't win or lose the political battle for us by itself. No matter how it turns out.
-Here I disagree. If the coalition wins easily, the political battle is -lost, at least for now, althought the USA still can have a troublesome -occupation (but then we are back with the necessity to have casualties -for the US occupation troops)