Hillary Clinton

Unrelenting, fierce and armed with full-on opposition research against Obama; her focus appeared to be on Super Tuesday rather than on the South Carolina audience. Yet at times seemed heavy-handed, cutthroat and even mean-spirited — ending any lingering idealistic thoughts about a Clinton-Obama ticket. Able to switch effortlessly from merciless attacks to smooth, upbeat self-promotion. When the talk turned to substance, energetically plunged into a weighty discussion of the economy and health care. Was never visibly rattled — even when booed by the crowd or when challenged by Obama, who played surprise cards such as her service on Wal-Mart's corporate board. Seemed steely and sturdy, but the fiery debate overall may have left a bad taste with the voting public.

Bottom line: She was a well-prepared pro, eager to draw Obama into a fight (with her husband in the wings ready to take up the sword).

—By Mark Halperin