Barack Obama

His best debate performance so far. Stood up to sustained questioning on his alleged inexperience, which led the first seven minutes of the event, without losing his cool or backing down. He even made a well-received joke about preparing for the debate by riding the bumper cars at the Iowa State Fair. Tripled down on standing up for his recent controversial foreign policy statements on nuclear weapons, meeting with foreign leaders, and hunting al Qaeda, with firmness and good humor. Drew audience applause for again playing the I-opposed-the-Iraq-War card to tout his judgment. Sounded almost (Bill) Clintonesque in talking about trade and merit pay for teachers. Displayed the confidence of a leader.

—Mark Halperin