Frum poses the question:

What presidents must inescapably do is respond to emergencies: eg, the financial crisis of 2008, the 9/11 terror attacks, the financial crises of 1997-98, the invasion of Kuwait, etc. And there, what usually ends up mattering most is not the president’s philosophy, but his judgment, coolness and steadiness. Those are the grounds on which Romney reassures and Gingrich terrifies.

Earlier thoughts of Newt's finger on the button here.