You have to do something powerful or dramatic to get them to take a new look at fresh facts. I think if McCain would campaign in Iraq for weeks leading up to the GOP nomination, it would be unique, daring, and too hard to ignore. He would force news agencies to report on it. Remember, every news agency in the english speaking world has a correspondent assigned to McCain 24/7/365. They follow him on a plane everywhere he goes. They have to file at least one report every day. Drag their sorry asses to Baghdad, or Ramadi, and every day highlight your greatest asset: competence, consistency, and steadfastness on the war on terror. Each day you also highlight Obama's weaknesses: naivete, wrongheadedness, and cut-and-run tendencies and outright policy. At each stop mention that Obama would have left these poor souls to the tender mercies of al Qaeda, and imagine what an al Qaeda controlled Iraq would mean to oil markets (e.g. the gas pump) right now? At each stop he could also contrast a little with the unpopular Bush by saying that all along he was for more boots on the ground up front which, ostensibly, might mean we would be further along than we are (I would argue that point, but the sheep would buy it).
The other thing this highlights is McCain’s courage and maverick tendencies: it makes this a race between Teddy Roosevelt and Chamberlain (or Elmer Gantry). My money would be on Roosevelt, wouldn’t yours?
That would be a Secret Service and security nightmare. That could cause an open convention.