David Gergen: “If the charges relate to collusion or conspiracy against the United States... that's going to send a shutter through the…”

It's very, very big. Not legally, but politically, it's a very, very big deal.

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

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

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…