The GOP is the largest political machine in the country with three main divisions within the party. The Tea Party, the Libertarians, and the Evangelicals. Yes, there are the few "moderate" Republicans that do not fit into either of those groups, but they are a vast minority and are ignored by everyone except the Democrats.
The Tea Partiers are the politically illiterate, extreme conservatives in the GOP. These are the people who do not get why everyone else laughs at them when they yell "Keep the Government out of my Medicare". They are often poor people who want tax breaks for the rich. The Libertarians aren't officially GOPers, but vote along Republican lines most of the time. These are the people who worship Ayn Rand and her adolescent-minded "mine-mine-mine" economic philosophy. Their unofficial motto is "F*¢k you, I got mine!" Next are the Evangelicals, who are the descendants of the Moral Majority. They use the Bible and their version of Christianity to rob the poor, discriminate against gays, insert their deity into everyone else's life, usually through schools, and to get rich.
And what is so bad about Ted Cruz? For one, he is the epitome of the dishonest politician. PolitiFact.com rated 87 of his statements and only one was "true" and very few others "mostly true." In other words, he lies constantly.
Imagine if you will what the liberal version of Cruz would look like. She would be a Wiccan, anti-vaxxer, anti-GMO, Maoist, and a radical feminist (the man hating kind, not the equal .rights kind). They're out there, but they're not running. Why? The Left wouldn't back such an extremist. So why is the Right backing someone like Cruz?
The initial response is that the GOP is made up of idiots. This is not the case. Out of all of the parties, the GOP is the most politically shrewd. They know how to play politics to get what they want. As a minority, they almost defeated the Affordable Care Act. in 2009. While they were not able to defeat it, they were able to gut it, making the AFA a shell of what it could be. This has made their campaign contributors quite happy.
But in the past four years, four states have legalized marijuana, and several others have decriminalized it in moderate amounts. The country is more secular with the number of religious "nones" at just under 20%. The gap between the highly rich and the highly poor is not only widening but the number of poor is growing. Yet we are a wired nation. We KNOW about these things, and we are tired of the inequality. Just a few years ago, it was unthinkable to give gays the right to marry, but now, most people support it. This is proof that the GOP is losing touch with the heartbeat of America.
And who could such a candidate be? He would have to be a moderate conservative, a relic from the '90s and early 00s. He would have to have some minor support for things like immigration reform, recognizes gay marriage, is all for Common Core, and is somewhat environmentally friendly. A spouse who's a minority would get some swing votes, and so would if his own party lambasts him as being a Republican In Name Only. But which candidate could that be? One who would be un-electable because his father and brother were President.