From an interview in 2000 with Jim Leher:
Lehrer: Finally for the record, you have not lost your desire to be President of the United States have you?
McCain: Certainly it’s been put in deep cold storage. haha..
Lehrer: You haven’t lost it?
McCain: Well, in 2004, I expect to be campaigning for the reelection of President George W. Bush, and by 2008, I think I might be ready to go down to the old soldiers home and await the cavalry charge there.
http://www.crooksandliars.com/2008/05/23/in-2000-mccain-admits-hed-be-too-old-to-run-in-2008/