I'm going to argue this from a purely pragmatic, Machiavellian, morality-shmorality point of view.
End the war on Bush's watch, force him and the Republicans to eat their defeat (and it is their defeat.)
Step one is to outline what it would take for the United States to really, actually win in the way that gave neocons wet-dreams 4 years ago. Step two is, give Bush and the Republicans a clear, honest choice: either
do what it takes to "win" the war
"get off the pot": end the occupation.
Let's define "winning" as...
- Violence reduced to Pre-war levels;
- A stable, secular, united central government in Baghdad;
- Infrastructure (power, water, food distribution, sewage treatment, etc.) equal to, or exceeding, standards that obtained in pre-war Iraq.
...thus providing the example of freedom that would be (highly debatably...) attractive to Arab populations living under dictatorships in the region.
How could the United States (and, given the level of support the United States could realistically expect from the rest of the world, it would be virtually the United States alone doing this) get there from here? What would it really, actually take to completely pacify Iraq?
Step one is troops. Lots and lots and LOTS of troops. Bush's "surge" is comically inadequate to the task. You'd have to absolutely flood the non-Kurdish parts of Iraq with American troops, who could clear of insurgents, and then seal off to weapons smuggling, the whole of Iraq, village by village, city by city, region by region. You'd also have to effectively seal off, or at least monitor in fine-grained, very intrusive detail, the borders of the country, especially the ones with Syria and Iran - to the point that a ball-point pen couldn't enter the country without American say-so.
This means anywhere from tens to hundreds of thousands of combat troops - in each large city in Iraq. Baghdad alone would probably need something in the neighborhood of 200,000 troops, just for the city itself. Plus, every road into Baghdad (and every other city in Iraq) would need to be under 24-hour patrols and surveillance, to prevent insurgents and weapons from moving from place to place. Not to mention saturating every border crossing of any size with American troops, and regular, pervasive patrols of every mile of the border.
The population would need to be disarmed: the military would need to just say, "you have six weeks to turn in any weaponry. Any Iraqi civilian found to be in possesion of a weapon after that time will be presumed to be an insurgent, and will be subject to imprisonment."
In other words, the American Military would need to effectively run Iraq in the short- to mid-term. The total American forces in the country at any moment would probably total somewhere between one and two million troops.
Step two: Once the violence was quelled (and, with sufficient troops, it would be, probably with surprising speed): "turn the lights back on."
Prime targets of insurgents are electrical lines, to keep the population uncomfortable and inconvenienced, and thus resentful. So, rebuilding existing generating capacity, building new capacity as needed, and then putting power stations, and every mile of power line, under 24-hour guard, is essential to undermining support for the insurgents.
Next, restore basic services: Water, sewage, garbage collection.
Garbage collection especially would improve life measurably for the population, in a highly visible way, and would be rewarded with lots of goodwill. Garbage collectors are prime targets of insurgents, because garbage piles by the side of the road make good hiding places for IEDs.
Step 3: Send the vast, vast majority of the American contractors in Iraq home, and hire Iraqi companies for all future rebuilding projects, and pay them in dollars. Iraqi unemployment is somewhere north of 50%, and unemployed men (especially former Iraqi Army soldiers) are ripe for recruiting by insurgents. Employing them would dry up this particular resource for insurgents, and also give Iraqis a sense of ownership of the projects they would be building. Even people not involved directly in building schools, post offices, etc., would see them being built, and have a clear sense that everyday life is getting incrementally better.
All this would, of course, be hideously expensive - hundreds and hundreds of billion dollars, every year. There would also be a sharp spike in American casualties, but the insurgency would probably melt away in the face of pervasive American troops, so the spike would be significant but temporary.
Also, some of those casualties would be draftees, because summoning the level of troops required for all this would require a draft (and a big one) without question: a level of mobilization not seen since World War II.
Once some semblance of stability was achieved, a scheme for governing Iraq could probably be forged.
So, Democrats could say: "24 years ago, a Marine general in Lebanon put it more eloquently than we ever could:
'If you have sent us here to fight, we are too few; if you have sent us here to die, we are too many.'
Here's a realistic plan for success in Iraq. We'll be sending the President two bills: one to end the occupation over the next six months, the other to do what it takes to succeed in his mission in Iraq, using the metrics that he himself defined."