No own denies that Cruz is a US citizen.
It’s his natural born citizenship that is in question.
It has been argued here endlessly
The Democrats don’t care.
It’s an avenue for them to attack Cruz
Scalia : “Isn’t a natural born citizen born in this country ?”
http://www.wnd.com/2012/08/scalia-flummoxed-about-natural-born-citizenship/#yKbd8Q52LVWhufMh.99