Its time to face up to the facts: not only has the war in Iraq been executed terribly, but we can hardly hope to have a decent outcome unless we chin up and put down the requisite resources:
Perhaps, at the beginning of the occupation phase of the war, 150-200,000 might have cut it. There was still an army leftover from Hussein, and most of the institutions were intact. Then we fired all the Ba'athists, let those looters run free, slipped up a few more times... and now we're dealing with full-blown militias, a very effective insurgency, highly-developed terror organizations, sectarian strife and huge amounts of criminal activity.
Fortunately, we can cope. Using the right tactics and sufficient force one can bring about security. Unfortunately, you need to maintain that force while expanding the secure area until the insurgency, militia, criminals, terrorists, have nowhere left to run. That's not being done. The situation was recently aptly summarized in a NYT article:
"...counterinsurgency operations have taken on the quality of a whack-a-mole arcade game. Every time the Americans have massed force to put out one fire, they have created a vacuum elsewhere that the insurgents have rushed to fill. When the Marines gathered forces to clear Falluja in 2004, they drew troops from the Haditha area, where the insurgents promptly moved in and executed the defenseless local police near the town's soccer field. The Marines returned in strength to Haditha and established several forward bases, including the one at Barwana, but then many of the troops were sent to the far west when commanders decided to clear Al Qaim, near the Syrian border. And the insurgents filtered back to Haditha."
Once we've established security, economic activity and free-discourse can escalate to the point where Iraq can become a viable democracy, but we simply cannot establish security given our current manpower.
Currently, the American army is trying to substitute for the shortage by beefing up the Iraqi military and police forces, but unless we pull off a miracle (if we do, I won't complain), that just is not going to work.
In chaotic situations, it is very difficult to impossible for a decentralized-democratic government to impose order.
Take, for instance, the Russian Civil War. In that war dozens of democratic rights-abiding governments rose from the chaos of Tsarist Russia, only to be crushed by terror-driven, highly disciplined conscripts from a centralized dictatorship. Ultimately this dictatorship was the Bolsheviks but Wrangel, Denikin, and Kolchak all also had their time in the sun as dictatorial White autocrats (of course all promising democracy as soon as the Reds were defeated, to be fair to their legacy).
So, if left to fight for itself, there is almost no way Iraq's government can establish order without resorting to dictatorial measures.
Which is why they need us. They need us to provide the security normally only a dictatorship can attain while their nascent democratic institutions find their feet. To provide that security, we need more soldiers.
The failure to do as much has been the Bush administration's ultimate fault in Iraq. And it's not like we cannot either. In the first Gulf War, we put forth 500,000 soldiers- and that was just to liberate Kuwait. In this war, yes, the sacrifice of our soldiers has been great, probably too great in light of the harvest we are reaping, but the sacrifice of our nation on the whole has been negligible if not laughable. No extra taxes have been imposed- in fact I believe we've enjoyed several tax cuts, nobody has been asked to put forth a little more, American society on the whole is operating on a peace-time basis- fighting this war with one hand behind the back, so to speak. I'm not saying that we should go into World-War total-war mode, but only that the resources we can bring to the table in Iraq are much more immense than what we have brought to bear.
So, Mr. President, get a spine and put in the troops. You won't get popular support- Americans don't trust you with military operations (I wonder why...?), but what does it matter? Your poll ratings are low anyway and you don't have to get re-elected. Chin up, belly in, and face the electorates wrath. If we upped the number to 500,000 and our military commanders don't suddenly lose their minds, we will see results. In fact, we might even get a viable democracy in Iraq.
Perhaps you're just waiting for December...?