Trump isn't a break with previous GOP behaviors. He's the next logical step. Here is Cassidy in the New Yorker:
In the past, Republicans cleverly obfuscated the regressive nature of their economic platform by appealing to social issues, and quietly playing the racism/xenophobia card. Trump, however, is beating his rivals at this game, too. On social issues, he has demonstrated that you don’t have to be a Bible-thumping pro-lifer to attract the vote of evangelicals. On immigration, by promising to round up and send home eleven million undocumented workers, he has trumped even the Cruz wing of the G.O.P. And in playing to white hate groups and other racists he is doing what other Republicans, particularly in the Deep South, have been doing for generations. But, while many of these Party regulars used a dog whistle, Trump is using a foghorn.