The McCain candidacy was a result, not a cause of COP problems.
You have to go back even further. If the Republican Party had not nominated fake conservative Bush, but a REAL CONSERVATIVE, there is NO WAY that ALL THREE BRANCHES OF GOVERNMENT would have fallen to socialists.
IMHO the GOP implosion began at a very specific moment in time:
That moment, was when George W Bush called those Republicans who had voted for him, supported him and considered him their inspiration: “Vigilantes”.
Then, threw those two border agents in jail, sucking up to Mexico to such an extent - as to utterly demoralize the entire conservative movement in America.
That was the beginning of the GOP’s current mess.
For all the good things George W Bush did - he really jumped the shark on globalism.