Yes. Seriously. Race.

Trump refused to rent to black Americans. Trump retweets white supremacists. Trump stated that a judge wasn't fit to preside over his Trump University fraud case because Judge Curiel is of Mexican ancestry. Trump ran a years long birther campaign. Trump called Barack Obama a racist. Trump is so deep in his projection that he even called Bryant Gumbel racist. By "called" of course I mean "tweeted" since Trump doesn't have the sack to make these accusations to people's faces.

Did you think David Duke, Richard Spencer and the global neo-Nazi movement were drawn to Donald Trump because of his reality TV career, his foreign-manufactured ties, his bankruptcies, his repeated stiffing of his blue collar contractors, or his many twitter opinions about Katy Perry's love life?