Sen. John McCainJohn Sidney McCainRubio asks Army to kick out West Point grad with pro-communist posts The VA's woes cannot be pinned on any singular administration Overnight Defense: Mattis offers support for Iran deal | McCain blocks nominees over Afghanistan strategy | Trump, Tillerson spilt raises new questions about N. Korea policy MORE (R-Ariz.) spoke from Baghdad Sunday with "cautious optimism" about the progress a surge in U.S. forces has produced in Iraq, having become cautiously optimistic during what the Washington Post described as "a heavily guarded walk through a newly fortified Baghdad market." But McCain added wisely, "I am not saying 'Mission Accomplished.' ... we have a very difficult task ahead of us."

As McCain struggles to keep his footing in the presidential race he led until recently, progress in Iraq is key to progress on the ground in Iowa, New Hampshire and other political battlegrounds for this war's strongest supporter. He must tout each incremental success in the face of an increasingly emboldened opposition party in the Congress and an angry, disheartened public, even as politicians in Iraq have begun to conclude that American forces are on their way out sooner rather than later.

The question that keeps coming up is what happens post-surge, when reduced security allows the violence to surge once more? Last week a military expert who had just returned from the region expressed the same sentiment as McCain. He told me he saw significant improvements at the hand of Gen. David Petraeus, to whom he gave high praise. But he said there is also the possibility that Moqtada Al Sadr, who has retreated to Iran, can wait out the American occupation and return to find our forces have done his work for him by clearing Sunni insurgents from Iraq.

When I asked a Republican lawmaker also supporting the war about this theory he said he hopes there is a chance while Sadr is gone for moderate Shiites to forge a coalition stronger than Sadr's before his return by rejecting a theocracy and choosing instead to become a dominant hand in a democracy.

That optimism is not what I would call cautious.