Sooooo - his message from now until November needs to address his substance and capability to govern. He could do worse than site other examples of successful governors who've come from such a background, beginning of course with that "inexperienced" (if not exactly unknown) guy in California a few years back...whatzisname...yeah, RW Reagan.
I respectfully think you're looking at this thing backwards. Despite being a powerful, well funded incumbent, Gray Davis only captures 34% of the vote. I can't remember the last time I saw numbers that low. Rod Grams (R-MN), I believe, was about 40% and he was considered DOA. (Turned out to be an accurate prediction, too).
There is still approximately 19% of those polled who are apparently in the undecided category. Plenty of room for either candidate to rise.