Their perception will change regardless. This will be a boon short-term for Ds as more of the kids will lose lives, but in the end, if they actually do what they say they will (I don't think there is enough of a surge to do it quickly) the change will be abrupt.
If the "more of the same" crowd continues on that tack they will find themselves floundering at sea.
I believe in preemption in politics, to view a longer picture and to change tactics when necessary. If your goal is to end the war, pretending that the surge wasn't in the report when it can be clearly pointed to, or that it is not a change when it will change the reality in Iraq, will not work long-term. But heck, I'm not a Democrat, why give you guys advice? Because I don't think it is worth the loss of life in a run-around the constitution War Powers Act "war"...