"A Consular Report of Birth is proof of United States Citizenship by law: 22 USC 2705"
So is a passport.
But a CRBA is not required to prove citizenship. Cruz could have gotten a US passport by submitting his Canadian Birth Certificate, his mother’s US birth certificate, his parents’ marriage certificate and a statement from his mother stating she met the residence requirements.
If they had gotten a CRBA back when he was born they would still have needed to provide those documents.
And under that:
"The following documents shall have the same force and effect as proof of United States citizenship as CERTIFICATES OF NATURALIZATION or of citizenship issued by the Attorney General or by a court having naturalization jurisdiction:
(2) The report, designated as a Report of Birth Abroad of a Citizen of the United States, issued by a consular officer to document a citizen born abroad. "
Perhaps this is why he won't produce his CRBA ( if he has one ). It will show that by having a CRBA, he is NATURALIZED.