There is significant frustration in the GOP base that a RINO looks like he will be elected. He is liberal in so much of his philosophy. If McCain is nominated I doubt if many will vote for Hillary but there will be a significant number that will either vote third party or just not vote. The GOP establishment is convinced the base will come along and thus has no problem with a RINO. They appear to care more about GOP control than about GOP philosophies such as controlling the border, low taxes, free speech, energy independence, judicial restraint, etc.