Texas Sen. Ted Cruz on Thursday offered an impassioned defense of his vote to rein in the government's bulk phone surveillance, blasting those in his party who he said wanted to "exploit the current crisis by calling on Americans to surrender our constitutional liberties as the only way to ensure our safety."The Republican presidential candidate, who has been gaining in recent early-state primary polling, used a speech at the conservative Heritage Foundation to respond to criticism from two fellow candidates, Florida Sen. Marco Rubio and New Jersey Gov. Chris Christie, for his vote to end the National Security Agency's mass...