. >> given the choice between neo-isolationism or the defense of our country, he's chosen neo-isolationism. whether it's weakening our intelligence-gathering capabilities, or voting against the defense bills, or voting against a budget that substantially reduces our defense spending-- these are facts. >> reporter: while they duke it out, new jersey governor chris christie is also on the rise, stressing his time as a federal prosecutor. >> and i was, you know, in charge of having to make many of those decisions in my office in my seven years as u.s. attorney. >> reporter: the new security focus, of course, also sparked donald trump's call to block muslims from entering the country, and that prompted new criticism from some of his opponents, like ohio governor john kasich. >> look. people don't buy this. >> reporter: ...and former florida governor jeb bush... >> there's no evidence he's serious about any policy proposal he's laid out. >> reporter: so far, though, the national security debate has seemed to boost, not bruise the republican frontrunner. >> we have to get smart. we have to get t

cruz and others, not just him, have been given a choice between neoisolationism, he's chosen neo isolationism against the defense bills or voting for a budget that substantially reduces our defense spending. these are facts. >> there if you have rubio painting cruz as what he calls a neo isolationist, this appears to be an escalation in the fight between them. and next week we head to vegas for the next republican debate. you'll see fireworks between the two. rubio got in another little dig implicitly at cruz when he was asked about whether he would say something at a private fund-raiser that he wouldn't say in public. this clearly an allusion to this "new york times" report that's out today saying that senator cruz at a private fund-raiser in new york appeared to question the judgment of donald trump. as you know, up until now cruz has really shied away from going after trump or saying anything negative about trump. cruz said in the course of a presidential election, the voters will make a decision about every candidate and ultimately the right is the one who has the experience to serves a c