John McCain

Best: Got some of his mojo back. Several answers — especially on twin vulnerabilities of Iraq and immigration — channeled his genuine views and transcended mere debate prep. Sold bipartisanship, hard choices, fiscal discipline, anti-torture, and experience — all his aces.

Worst: Pushback against Romney's attacks on his support for biparitsan immigration and campaign finance bills summoned up the peevish ghosts of campaign 2000. Speaking of 2000: planted seeds of a new Confederate flag problem with another evasive answer that he (probably) doesn't believe.

— Mark Halperin