I would say it started with Nixon. Nixon paved the way for Reagan. Recall that the two were often political allies. Reagan paved the way for the Tea Party by coopting the conservative Libertarian agenda of the Koch Brothers (one of whom was the VPOTUS candidate running against the GOP Reagan/Bush ticket). The Tea Party was just MAGA Trumpism before the tangerine turd gave them his name and orange countenance around which to coalesce like the putrescent effluvium that they all are.