David Gergen: “I think it undercuts John McCain's argument about not sitting down with Iran, being very tough on them.”

I think the turning point that came were the midterm elections. The fever broke with those midterm elections. And what we've seen since then is a steady decline in Trump's credibility and in his position with the American people, and a…

If he comes out and throws cold water on this, then I don't think it goes anywhere.

I think a lot of Americans do see it as disqualifying. And they're worried about it.

You can't out-Nixon Nixon very easily, but Donald Trump has.