Republican presidential candidate Ted Cruz is using video of former President Jimmy Carter against rival Donald Trump. A new ad released Thursday quotes Carter, who said Wednesday that if he had to pick between the two, he "would choose Trump" over Cruz. "Trump has proven already that he's completely malleable," Carter, a Democrat, continues in the clip. "I don't think he has any fixed opinions that he would really go to the White House and fight for. Ted Cruz is not malleable."