The Unholy Alliance
Those who are in positions of power in the Republican Party have one overriding principle, which is to gain and hold power. In pursuit of that aim, they appeal to various groups, members of which have a particular overriding principle, for example:
Cutting taxes ond providing tax loopholes for high income and rich people;
Cutting out government regulations that bother them;
“Taking back America”: transforming it from a liberal pluralistic society to a white-dominated one that institutes “Christian” values;
Belief that a “strong” authoritarian leader would make America a stronger, richer country;
Belief that measures to combat climate change are a form of tyranny;
Belief that gun safety regulations are alien to a free society;
Belief that people in lower income categories get too many handouts, which amount to work disincentives;
Belief that coastal elite types are screwing real Americans.
Convince the members of each of these groups that you are fighting for their special rights and interests, and you can put together a winning coalition. The Republican Party is an unholy alliance but an effective one.