"The primary voters vote for candidates who have already been nominated,by the party."
You have a profound misunderstanding of how the nomination process works in America. Individuals run in the primary of a particular party, and the voters who belong to such party select the nominee. The party chairman was NOT appointed in order to determine who the party's nominees will be, and having the chairman (or the committee or what have you) decide who may run in a primary can lead to all kinds of abuse.
BTW, the GOP chairman did not pick Arnold as the party's standardbearer to the exclusion of others. The CA recall election allowed anyone who could get 100 signatures or something to run regardless of party, and Arnold, McClintock and several other Republicans were all running (like you, I supported McClintock, and I think I'm going to send him some more money now that he's running for Lt. Gov.). In 2006, however, California will have a normal gubernatorial election, and each party will hold a primary to determine its one standardbearer. If a Republican chooses to challenge Arnold in the primary, he or she is free to do so, and the state's Republican voters will decide who gets the nomination. However, imagine if Condi Rice challenged Arnold for the gubernatorial nomination (I can dream, can't I?) and Parsky and the rest of the RINOs who run the CA GOP decided that she could not run in the primary because "she's not a real Republican" or "nobody should challenge Arnold" or some other cockamamie excuse. How would you feel about that? By what right could Parsky et al disrespect the millions of California Republicans?
If a political party selects its nominees in a primary, then the party should not prohibit certain candidates form running, period. The primary voters will decide for themselves whether that candidate is or is not loyal to the principles of the party.
Actually, my hope is, by 2020, the words Republican Primary and Election will become indistinguishable
It's ridiculous that we have to have three sets of elections instead of two like the olden days.