Then, six hours later, his senior economic advisor says it's eight years, not four:
"The senator has always pledged to balance the budget by the end of his second term."Thereby making it appear that he hadn't fliped and flopped back and forth on the timeline. Which is it? Who knows! That's Strategic Ambiguity at its best! No one can get angry at you for breaking your word, because you never gave a clear word on the subject. Brilliant.
Either that, or McCain knew that it was supposed to be eight years, and forgot on the way to the podium.