Hagel and McCain

Republican Senator Chuck Hagel spent Sunday talking about why he isn't waiting in line to endorse McCain. The reason? They don't agree on the Iraq War, where Hagel has diverged from his party for a while. He did not slam the door on the possibility of supporting McCain in 2008, but The Hill points out that Hagel was one of McCain's presidential co-chairs in 2000. Is it Hagel or McCain that has changed? Or did the Iraq War just reshape everything?