Edit: Image is from this Reuters article deconstructing Trump’s latest rally.
As late as 1980s, the GOP had a Liberal wing. Once Reagan got his claws firmly embedded the Right was able to marginalize or remove them.
There’s an old saying in US politics; Democrats fall in love and GOP fall in line. GOP will vote for any candidate with an R next to their name, and the Dems want someone they can get excited about.