I have no idea, but he said it. But he's said a lot of crazy things - like believing in time travel. Maybe Wesley Clark actually was a Republican in the future.
I suggest you read this Newsweek coverstory where Clark was quoting as having said it.
http://216.239.57.104/search?q=cache:YWrsgCb8JugJ:www.msnbc.com/news/969659.aspMSNBC removed the story and I could not find it in the archives. Maybe Newsweek stories run for a limited time only, or maybe they were whitewashing for Clark like so many here are trying. I don't know.
But I found the story archived on Google.
It has crossed my mind a few times though. What if Wesley Clark is NOT the Clinton's candidate, but actually Karl Rove's candidate instead?
The bottom line is Wesley Clark just doesn't have enough of a political history for us to know one way or another.