The law about CRBA says that a passport will also suffice.
Cruz has a passport, I assume. I don’t really know, but I think he was out on a foreign trip last year.
Saying Cruz is not a citizen is a non-starter. First, even if your parents didn’t fill out the paperwork, then it used to be you could do so until age 23 or so, but now I think there is no age limit at all.
So, his passport is evidence of his US citizenship.
I’m a Trump supporter, by the way.
We also know that Cruz was a citizen of Canada at birth thru birthright citizenship. It was less than two years ago that Cruz formally renounced his Canadian citizenship. Why he didn't do it sooner is something of a mystery to me. He was a dual national for most of his life. The matter really needs to be litigated in the courts.
But “citizenship” is not the issue. “Natural born citizenship” is the issue. It is the elephant in the room.