Well, he used to. Hat tip to the video-archiving freedom-haters at Think Progress:
Some Americans ask me, if completing the mission is so important, why don't you send more troops? If our commanders on the ground say we need more troops, I will send them. But our commanders tell me they have the number of troops they need to do their job. Sending more Americans would undermine our strategy of encouraging Iraqis to take the lead in this fight. And sending more Americans would suggest that we intend to stay forever, when we are, in fact, working for the day when Iraq can defend itself and we can leave. As we determine the right force level, our troops can know that I will continue to be guided by the advice that matters: the sober judgment of our military leaders.
That was 18 months ago, when an escalation might have had more of an impact. Curiously, some people ask why this "surge" idea isn't being taken seriously. (Another reason for that here.)