This is actually a re-run of the cycle of American anti-immigrant fear of past ages. The Know Nothing Party of the 19th century, the fear of the Irish, the Yellow Peril, the Italians, the Jews, it has been a re-circulating political football sometimes played as touch-down, other times played as keep-away.
It's pretty terrible, but it isn't that new, and it is not going to devolve into a neo nazi thing of any strength, it has simply gotten the hopes up of some really hopeless (as in mentally/morally/politically deficient) people.