nominee. mark: bush hitting trump in a new ad. what is his challenge for tonight? john: i think in this point, his attempts to become the anti-trump has not worked. he needs to focus on the other establishment candidates. mark: i think the challenge is not going after trump versus going after others, it is going after trump versus going after his establishment brand. i think if there is an opening to get trump, he has to do it, but this is the time for him to go back to the principles of his campaign and say, i am the adult in the room. john: let's move onto to marco rubio. he is the one that is best positioned. what is his challenge tonight?