Troop Withdrawal and Campaign Promises

John McCain's been consistent in claiming he won't draw down troops in Iraq until "victory" is guaranteed, whenever that might happen. Barack Obama says he's been consistent too, but Republicans claim it's a flip-flop when he says his sixteen-month timeline depends on Iraqi stability. With reports that violence is decreasing, is Obama revising his plan?  Was McCain right about the surge?  Is Iraq's Shiite-dominated government making peace with Sunni insurgents, or could violence resume and upset the strategies of both candidates?