Rudy Giuliani

Wisely continued to run rhetorically against the Democratic field more than the other Republicans on the stage — a great frontrunner tactic that is the mirror image of Hillary Clinton's debate game plan. Once again attacked the liberal media and talked tough on crime and terror. Defended his record on immigration and gun control as mayor of New York — and his personal life — in a calm and dignified manner. Said he isn't running based on his 9/11 experience, but on his full record as mayor, including as a tax cutter and manager. Every time he comes under assault and doesn't stumble in style or substance, he gets stronger, and burnishes his image as both a frontrunner and a leader. Biggest chink: at times a bit more mayoral than presidential.

— By Mark Halperin