’Donald Trump is "politically incorrect" in many ways, from racist attacks on Mexicans and Muslims, to questioning NATO and praising Vladimir Putin. He's refused to endorse some GOP leaders even though they've endorsed him. So, why are Trump supporters rock solid, however outrageous he sounds? The answer may lie with millions of white Americans, and the economic anxiety and fear of cultural change ignored by both parties for too long. We hear about Trump's constituency — and the challenge it poses for both political parties, whoever wins in November.