Same sort of dynamic is at play with the government in general (yes, I know a political party is not the government). Technically, a political party IS the exclusive property of its leadership. What the leadership does is lie to the people in order to draw voters to its claimed causes. When that illusion breaks, people stop supporting the magical-party.
The party should look at case studies about how to handle a crisis. It is handling this one poorly.
-- It is well past time for a purge of party autocrats who have contempt for their own voters. --
Amen to that. Amen. From all outward appearances, the party has lost sight of its proclaimed mission, to serve its members.
Another way of looking at it, is that the voters are the Party's customers. The primary process is a way for the Party to find out what the customers want.
What we are seeing is the party deciding that the customers are too stupid to know what they SHOULD want, and deciding to shove their vision down their throats. The GOPE risks going the way of the Whigs, as the people are increasingly fed up.