It’s Iowa minus 32 days, and barring yet another resurrection (or event of similar improbability), it’s Mitt Romney vs. Newt Gingrich. In a match race, here’s the scorecard: Romney has managed to weather the debates unscathed. However, the brittleness he showed when confronted with the kind of informed follow-up questions that Bret Baier tossed his way Tuesday on Fox’s “Special Report” — the kind of scrutiny one doesn’t get in multiplayer debates — suggests that Romney may become increasingly vulnerable as the field narrows. Moreover, Romney has profited from the temporary rise and spontaneous combustion of Michele Bachmann, Rick Perry...