I posted this on Facebook last month and it's worth re-posting as people keep spreading this stupid myth.

Donald Trump is a liar.

There is not any question about Ted Cruz's citizenship, and Trump knows it.

https://travel.state.gov/

Acquisition of U.S. Citizenship by a Child Born Abroad

Birth Abroad to Two U.S. Citizen Parents in Wedlock

A child born abroad to two U.S. citizen parents acquires U.S. citizenship at birth under section 301(c) of the Immigration and Nationality Act (INA) provided that one of the parents had a residence in the United States or one of its outlying possessions prior to the child’s birth.

Birth Abroad to One Citizen and One Alien Parent in Wedlock

A child born abroad to one U.S. citizen parent and one alien parent acquires U.S. citizenship at birth under Section 301(g) of the INA provided the U.S. citizen parent was physically present in the United States or one of its outlying possessions for the time period required by the law applicable at the time of the child's birth.