One issue Trump hasn't exploited yet is marriage equality.

I suspect that some of the anger among his supporters is that this change happened so quickly, and they had no say in it. They shouldn't of course, have a say. You don't decide equal protection issues by majority rule. But they probably don't see it that way. Abortion and guns have had decades to get established as conservative issues, but their shock at the almost instant change in rules re gay marriage probably is under some of their rage. 

It's amazing that this hasn't been mentioned in the Republic debates.

This idea became clear to me as I work my way through Season 2 of Transparent. Not going to spoil anything, so don't worry. I almost gave up on it in episode 4, I was so tired of the characters. But then it got good, real good. And if you know what Transparent is about, you understand how I made the connection to Trump. It's remarkable that they wrote this season long before Trump had a serious following.

Marriage equality is a big issue for them, but it hasn't been talked about yet. I can't imagine Trump will stay away from it much longer, so watch out.