You are right...but, I seem to remember (but, my memory is faulty sometimes)...that a year or so ago...someone pointed out to McCain that something he was advocating, (probably the torture bill)...
would anger his conservative base...and he commented at that time, that he really wasn't worried about the conservative base.
I know I have had that remark stuck in my head for a while...but if you ask for the source...it MIGHT find it by next year....LOL
He has a rude awakening, unless a lot of dems register to vote as a Republican in the primaries... how many states allow you to voter either/or? I don't know.