Tom Cotton has "no regrets" because "if the president and the secretary of state were intent on driving a hard bargain, they would be able to point to this letter and say, they're right."

"When past senators like Joe Biden or Jesse Helms communicated directly with foreign leaders, past presidents, like Ronald Reagan and Bill Clinton, did just that. The fact that President Obama doesn't see this letter as a way to get more leverage at the negotiating table just underscores that he is not negotiating for the hardest deal possible. He's negotiating a deal that is going to put Iran on the path to a bomb, if not today or tomorrow, then 10 years from now."

On "Face the Nation" this morning.