In the coming weeks, Mr. Gingrich needs a better and more consistent message. He’s already won over everyone he was going to get by bashing Mr. Romney as a “pro-abortion, pro-gun-control, pro-tax-increase . . . Massachusetts liberal.” The self-proclaimed “bold Reagan conservative” must offer more than nostalgic references and calls for moon colonies.

His campaign must be more about his ideas than his emotional state. After Tuesday, he’ll need a clear explanation of why he should be the not-Romney rather than the issue-focused and increasingly likable Rick Santorum.

Newt Gingrich has been a consequential political leader for 30 years. But counting on his Southern strategy is hoping to draw an inside straight. And after his impressive hat-trick victories Tuesday, Mr. Santorum is, for the time being at least, Mr. Romney’s main challenger.