 A sitting president will face off against a former president, and the rules this time are a little different, says ABC national correspondent Stephen Portnoy. The two lecterns are spaced just eight feet apart. The 90-minute debate will feature two commercial breaks. No staffers will be allowed on stage. A two-minute answer to each question will be followed by a one-minute rebuttal, and then a response to that rebuttal. CNN has agreed to mute the microphone of the candidate who isn't recognized to speak.