"If we don't have a nominee who can win on the first ballot, I'm for none of the above," Boehner said at the Futures Industry Association conference here. "They all had a chance to win. None of them won. So I'm for none of the above. I'm for Paul Ryan to be our nominee."

I mean, that says it all. It's absolutely possible we end up in a brokered convention. Should that occur there is every reason to expect the GOP establishment to put up one of their own who is neither Trump nor Cruz

It's also possible that the old guard GOP decides to run someone as a 3rd party candidate, and that someone could be (though I would find it surprising) Paul Ryan.