I basically agree with what Marty Lederman is suggesting
in the comments to this post. The Democrats should pass something limiting the number of troops in Iraq. Bush will veto it. Republicans will make sure there aren't enough votes to override the veto. Stopping CooCoo Bananas from sending more troops is likely, in practical terms, impossible in the short term at least. But they can make sure it's clear whose war this is, and whose plan it is.