New Hampshire political scientist Dante Scala said the relatively flat turnout in New Hampshire could have been a reflection of the lack of serious competition there for Romney, who led from the beginning.
"Even if Republicans are not overwhelmed by the field in New Hampshire, they found Mitt Romney perfectly acceptable," said Scala, adding that Obama will face his own enthusiasm issues in the state, where independents have soured on the president.
McDonald, the George Mason professor, said Romney turns out more voters in large urban centers and suburban areas, while Gingrich shines in rural areas. No matter who gets the nomination, he says, "that candidate's going to have to heal some wounds within the party" to generate the broad kind of turnout needed to prevail in the fall.
AP writers Holly Ramer in Concord, N.H., and Jim Davenport in Columbia, S.C., contributed to this report.
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