Since few Democrats in Congress have backbones, here is a way to protest yet still appear, um, wimpy? supportive? hell, I don't know.
First order of business, when Congress returns, introduce a bill that STOP-LOSS can ONLY be used in conficts that receive a FORMAL CONGRESSIONAL DECLARATION of WAR. That would eliminate police actions, UN actions, incursions, etc. Then, if its important enough to commit troops AND prevent them from leaving when their scheduled to, then it's important enough to declare war.