donald trump nervous, also after cruz made some comments at a private fundraiser in new york really questioning donald trump's judgment and readiness to be commander in chief. cruz, for his part, has said at least publicly he's going to stay away from criticizing donald trump. he said yesterday he does not want to get into a cage match with trump, so it will be interesting to see how this continues going forward. victor? >> all right, in south carolina today, we'll see what we hear from donald trump. sunlen, thank you so much. let's talk about this with cnn politics editor mark preston. we see this poll, mark, in iowa where trump is falling behind cruise, but the new york times/cbs poll, trump is far behind there. help explain to people what is that gap, because it's a significant one there. >> it is significant, and it's a very good question because it