Every state Hillary Clinton and the Democratic machine has won (especially across the South) has been because of the strong support from minorities. That is without a doubt Donald Trump's achilles heal. The Donald needs to shore that up sooner rather than later. It will clearly become the difference in victory and defeat in November.
Clinton's strongest base (firewall) against sanders and in a general will be the minority vote. Trump will assuredly need to pick a VP who has the ability to attract minority voters in order to build a diverse coalitions that is necessary to win.