Nothing. Nothing at all.
I was telling my Mom yesterday that the election will probably hang on the debates, and that the trick for Hillary was to simply allow Trump’s negativity to pass right through her while she addressed the voters directly.
Given the new “Love trumps hate” meme for her campaign, it would also be interesting to have her gently chide him when he starts lying “That’s just not true, Donald. You known, Duckie, when you talk people don’t understand a word that you’re saying. But you are quite good at encouraging them to believe that you’re saying what they want to hear.”
everdeepening 
A guy like Trump should poll about 8%. That the Republicans are pretending to take him seriously is a national catastrophe, already. That 40+% do not see what is wrong, even naked fascism rising right up through the oligarchic Americans, and do not know the difference between liberty and tyranny, that is already a national catastrophe. If this gets five points worse, it could be a world catastrophe, and we might lose a war. Republicans, divide the party!
The problem is that the moneyed classes in the Republican Party (including the degreed whites that Clinton has been pursuing) vote primarily for the benefit of their bank accounts. They have tolerated religious and social fundamentalism for decades now because they undergird a Congressional coalition that keeps taxes low. Clinton’s aggressive progressive platform is going to cause these people to grit their teeth and vote for Trump. Those low-tax voters haven’t figured out that their greed is earning them what they deserve: incompetent government that kicks the can down the road to their children.