It was very clear, even from long before Donald Trump got in this race, when he would talk to Republicans, the number-one concern they had about Jeb Bush was whether he was too rusty for this, and whether he was going to be strong enough to stand up to Hillary Clinton.

Hillary Clinton is got to make the case for herself that nobody else can make, and for voters to see somebody who looks more three-dimensional, that's not simply a caricature that had been sort of a part of the American dialogue for the last 25 years.

The difference there is that the [Donald] Trump number on change is so much larger than the lead that the other two have in their lanes. And that's going to be the challenge for those other two going forward. The other challenge for Marco Rubio, and this assumption that you're just going to get all those Bush and Kasich voters.

It was very clear, even from long before Donald Trump got in this race, when he would talk to Republicans, the number-one concern they had about Jeb Bush was whether he was too rusty for this, and whether he was going to be strong enough to stand up to Hillary Clinton.

If you're Chris Christie, who is governor of New Jersey, a state that obviously was impacted by 9/11, this gives you an opportunity to talk about how, as governor, you had to deal with terrorism and security issues.

The real problem with Donald Trump is, if you engage him, it will only make things worse. It's like - it's a little bit what you were taught as a kid to not engage the bully, because they will continue to pick on you.

I still think there's some tension . But it's pretty clear that, when the president made his statements as a candidate, he's following through with those as a president.