U.S. tries to keep "roller coaster" Iran nuclear talks on track as deadline looms
President Obama said he is "embarrassed" for the 47 Republican Senators who signed a letter to Iran warning that any nuclear deal could expire the day the president leaves office. The letter has become an issue in the negotiations to curb Iran's nuclear program. Secretary of State John Kerry met with his Iranian counterpart in Switzerland on Tuesday. Margaret Brennan reports from Lausanne.