I’m by no means sure it will fail. A certain notion of can-do pragmatism is deep in American political culture, and that kind of forget the problems of the past let’s roll up our sleeves and talk about what’s working now attitude has a certain appeal. But it shouldn’t work. And the reason it shouldn’t work is that a given military strategy doesn’t just “succeed” or “fail” in a vacuum, it needs to be understood in some kind of strategic context. If you understand the war as a giant mistake which created a large problem that’s now in need of a solution, that creates one set of ideas about what counts as a solution. If you understand the war as an opening salvo in a campaign to use the U.S. military to remake the Persian Gulf, then working becomes a very different matter.
That said, the politics of the war will depend, crucially, on the actual situation. Surge proponents presumably think things will get better and better, whereas skeptics are inclined to see these stormclouds on the horizon and wonder if it’s about to start pouring again. Thus you have two different political strategies built in large part out of different substantive ideas about how events are likely to play out. There’s just no way to do the political analysis without adding a substantive analysis.