The obvious and simplest question is, what part of his agenda do you fear?
Like him or don't like him, what do you fear? His promise to seal the border and get control of immigration? His promise to get us out of Paris and TPP? His promise to get rid of Obamacare? His promise to build incentives in the tax code to bring manufacturing back to the US? What part of his agenda do you fear?
Once that has been made specific, even a drone like Issa should be able to respond to a specific concern.
My only fear was that he would turn out to be a Democrat at heart. But so far he has stuck to his guns on just about every point. If anyone ever thought he would wilt under fire he has proven time and again that that's just not Trump.
In too many cases, I think RINO fears are over how violent Democrat pressure groups will react if they are ever told no - and Trump is scary because he plans to tell them no.