The question I really want to see asked at the next debate:

“Each of you represents a party with extremist elements. How would you each address the extremists of your own party (as you understand extremism)?”

And as a follow up:

“What do you each believe the other should have said but did not?”

And as a follow up to that:

“Based on what you just heard from your opponent, what additional things would you want to say to your own party’s extremists?”