If you don't win control the better candidates will go somewhere else. After all, there's nothing like going to work and being locked out of the committee meeting rooms, and excluded from all the meaningful organizational efforts.
You have a chance to help the Republicans win legislative control of the Senate. It might well result in an opportunist winning the Governorship (as if Governor Moonbeam isn't an opportunist himself) (giggle, giggle ~ oh lord do you have a mess of incompetent people running for office out there).
You may not want an opportunist as California Senator, but you can't let Obama keep control. We have to destabilize his coalition and destroy his ability to govern. Whatever it takes, that's what has to happen. To start with that means kicking Boxer out.
You can do that however you want.
Never vote RINO!! It ain’t rocket science!!