Seems the grand old party wants the second tier candidates to pull out* of the contest:

Republican gubernatorial candidate Bill Simon (search), under considerable pressure by the party to withdraw from the recall election and endorse front-runner Arnold Schwarzenegger (search), wouldn’t rule out that option on Sunday.

It is hard to tell just where Arnold fits in. He has named both a democrat and a republican as top advisors and at least one of his democratic opponents (a minor one) calls him a Bush republican:

With President Bush arriving in California for a two-day visit, Huffington branded Schwarzenegger a “Bush Republican through and through.”

The further right you go the more he is considered if not a democrat at best a moderate republican.
Maybe the fact the he is getting hit from both sides suggests that for him the labels are not very meaningful and that he is a centrist with some outlier positions. At least he does not need to use his potential governorship to get wealthy.