An enormous proportion of Republican
voters were already Trumpers as early as the ‘90s, but didn’t have a candidate yet, so had to settle for “vote Republican to keep the democrats from doing all the bad things Rush says they will”.
Republican partisan-propaganda media after anti-trust de-fanging (mid ‘70s) and media deregulation (‘80s-‘00s) became huge, and cultivated an electorate that wanted Trump but had to settle for tepidly-socially-conservative neoliberal Republicans. Such voters would tell you all day long about how we should just build a border wall (or mine it…), cut trade and foreign military engagements (though those have some cross-aisle appeal), question why we extend civil rights and due process to [pick a group], tell you we should use the military against protesters in cities, wonder why anyone opposes cops beating suspects unless they love crime, and so on, and they’d tell you that stuff many years before Trump’s 2016 run.