On Friday, Donald Trump threatened fellow GOP presidential contender Ted Cruz with a lawsuit over Cruz's eligibility to run for president:
Though Cruz, who was born in Canada to an American mother and a Cuban father, has maintained that he is a natural-born citizen and thus eligible to run for office, the constitutionality of his presidential run has been challenged — particularly by Trump.
However, Trump had previously promised that he would not sue Cruz over the issue. "I'm not bringing a lawsuit," Trump said at a January Republican presidential debate. "I promise."