hi clo,
the migration of more moderate republicans began under bush. these are the slowest movers.
there used to be a thing called conservatism which meant conserving existing institutions and innovating only with caution.
the metastasized thing also called conservatism is an ideology which has little in common with the original idea. it hates safety net government and loves government power (police, prisons, armies), believes in a magical ideal of unrestrained market forces, lauds wealth, blames the poor for their plight and thinks the usa has a special divine right to lead the world.
people who believe in traditional conservatism have no home among the right wing ideologues. rubio and cruz are the new republican party. trump is a variation on the theme, which takes the hatred of government one step further into hating the politicians who represent the anti-government view.
these folks are each capable of destroying the usa even more effectively than bush.
even sanders would not be as destructive. it's kinda odd to see the american people flirting so obviously with their country's demise. but heck, the romans couldn't resolve their constitutional problems either.