Sure let Trump roll with that and then Cruz can easily make him out to be a self serving political flip-flopper on Hillary and much else.
Keep in mind, Mr. Self-serving political flip flopper Ted Cruz is also relying on liberal interpretations of a "living constitution" to even be eligible. His attack, trying to act as if Trump is the stealth-Hillary candidate, won't be taken seriously by anyone who isn't a raving FR Cruzbot.