Without making a formal public announcement, moderate Republicans have left the party. A few remain, mostly out of cluelessness, some out of habit, some out of the deep-rooted shame in admitting that their lifetime-long voting patterns were at odds with what they believe, or any decent human being believes.
The vast majority of GOP voters over my lifetime, say the past sixty years, were in their hearts, racists and xenophobes, opposed to women’s rights, gay rights, and basic human rights–a good word for them might be “deplorables.” The decent ones, the self-aware GOP pols and voters, had to pander to this base in order to win elections, and they were successful at this magic act, gaining the votes of dunderheads, simpletons, yahoos, rednecks, and yokels while only sometimes giving them the political support they demanded. Sometimes the deplorables would triumph, but mostly they were frustrated with the elites who ran their party and who ran them.
Until Trump. He decided that since the deplorables were in the majority, he could break with traditional GOP leadership and actually give the deplorables what they wanted, an openly racist thug as POTUS, and they adore him for it. The moderates, a minority in their party, voted for him in 2016 because decades of reviling Democrats on principle left them without a viable choice, and slightly fewer voted for him in 2020 because they began to extract their heads from their netherregions.
The fact is that something like 30-40% of the voters in this country are irredeemable racist deplorables who longer have a GOP that pays them lip service but rather which espouses their deepest, foulest beliefs, and the other 10-20% that we call moderate Republicans or Independents are split between their old voting patterns and not voting at all, with some going as far as to hold their noses and vote for a Democrat on occasion.
But there is no going back for them, as far as the GOP is concerned. There is no longer a GOP that they can hope to control–there is only the party of deplorables, and the party of Democrats. They are not comfortable in either, and both parties are mistrustful of them.