Sorry Mr Broder - there is no middle ground

Defense policy analyst at the Council on Foreign Relations and an advisor to Gen. David Petraeus, Stephen Biddle says:
Iraq: Go Deep or Get Out

The president's shaky political consensus for the surge in Iraq is in danger of collapsing after the recent defections of prominent Senate Republicans such as Richard Lugar (Ind.), Pete Domenici (N.M.) and George Voinovich (Ohio). But this growing opposition to the surge has not yet translated into support for outright withdrawal -- few lawmakers are comfortable with abandoning Iraq or admitting defeat. The result has been a search for some kind of politically moderate "Plan B" that would split the difference between surge and withdrawal.

The problem is that these politics do not fit the military reality of Iraq. Many would like to reduce the U.S. commitment to something like half of today's troop presence there. But it is much harder to find a mission for the remaining 60,000 to 80,000 soldiers that makes any sense militarily.

Politicians and pundits alike are looking for middle ground. Take some troops out but leave a few for training. Biddle says nonsense:

The politics make sense, but the compromise leaves us with an untenable military mission. Without a major U.S. combat effort to keep the violence down, the American training effort would face challenges even bigger than those our troops are confronting today. An ineffective training effort would leave tens of thousands of American trainers, advisers and supporting troops exposed to that violence in the meantime. The net result is likely to be continued U.S. casualties with little positive effect on Iraq's ongoing civil war.

And he concludes with this:

If the surge is unacceptable, the better option is to cut our losses and withdraw altogether. In fact, the substantive case for either extreme -- surge or outright withdrawal -- is stronger than for any policy between. The surge is a long-shot gamble. But middle-ground options leave us with the worst of both worlds: continuing casualties but even less chance of stability in exchange. Moderation and centrism are normally the right instincts in American politics, and many lawmakers in both parties desperately want to find a workable middle ground on Iraq. But while the politics are right, the military logic is not.

The "surge" cannot be continued past March, 2006 - the US will simply run out of soldiers. The additional surge troop levels are not going to make any significant advances between now and them. That leaves one option - leave.