Sen. Marco Rubio of Florida (right) talks about his views on foreign policy at the Brookings Institution in Washington on Wednesday. He is joined by Marvin Kalb (left), a Brookings guest scholar, and Sen. Joe Lieberman, a Democrat-turned-independent from Connecticut. He discussed his views on Iran and Syria. (Associated Press)

Sen. Marco Rubio of Florida (right) talks about his views on foreign policy at the Brookings Institution in Washington on Wednesday. He is joined by Marvin Kalb (left), a Brookings guest scholar, and Sen. Joe Lieberman, a Democrat-turned-independent from Connecticut. He discussed his views on Iran and Syria. (Associated Press)