The inept handling of this has been his undoing. His defense is basically, "I'm NBC because I said so, and so did these other really smart people."
The problem is that opponents have trotted out their own really smart people who say, "Not so fast."
I know the Cruz base is really pissed at Trump for this, but you have to know it was coming. Better now than against Hillary (or whoever wins the D nomination).
PS. Cruz could have used some political cover from other respected politicians, all of whom have kept out of things. Their silence speaks volumes. Being an independent cuss is one thing, but it appears that he does not have any political allies who are willing to vouch for him.
He thinks that since Levin says so and will shout down anyone who dares ask the question it is settled. I have no idea, but it sounds like you have to be born inside the US with citizen parents unless you are in the military.