I disagree. Ted Cruz was a Canadian citizen. That is why he had to renounce it.
http://www.foxnews.com/politics/2014/06/10/ted-cruz-renounces-canadian-citizenship.html
Sorry. Not so.
Since Cruz did not appear at a Canadian Consulate (or the Embassy) and formally opt for Canadian citizenship at some point after reaching the age of 18, he never became a Canadian citizen.
The "renouncing" of same last year was for appearances, nothing more.