IT'S THE PARTY OF THE HEAD:

As Romney's team hoped, the Iowa result hobbled the two candidates it feared the most--Newt Gingrich and Rick Perry--while elevating the two rivals it believes are least capable of waging a true national challenge: Ron Paul and Rick Santorum. Paul, with his purist libertarian message, has an ardent but limited following. And although Santorum appealed to the conservatives who are most dubious of Romney (particularly evangelical Christians), the former senator didn't unify those voters nearly as much as Huckabee did. (He got 32 percent of their votes, compared with Huckabee's 46 percent four years ago.) In the contests ahead, the underfunded and lightly staffed Santorum also won't be able to replicate his Iowa strategy of virtually taking up residence in the state for a year. "He will get a hell of a bump" from his Iowa finish, said top GOP strategist Mike Murphy, who is neutral in the race, "but he has so much to do so fast."

If Iowa gave Romney any real headaches, it's because the state may have over-performed its historic job of winnowing the presidential field. The caucus results prompted Michele Bachmann to quit the race on Wednesday morning, less than 12 hours after Romney was declared the narrow winner. And although Perry has apparently reversed his initial inclination to examine withdrawing, the fact that he considered it underscores how much his fifth-place finish damaged his viability. Those developments should increase Santorum's prospects, starting in South Carolina on January 21, of unifying evangelical Christian voters who resisted Romney last time and showed no sign of warming to him in Iowa. "Romney's fear 

is that this consolidates," Keith Nahigian, Bachmann's campaign manager, said before she withdrew.

Evangelical voters alone would not be enough to make Santorum a genuine threat to Romney. But if Santorum, with his regular-guy persona and lunch-bucket message of restoring American manufacturing, can also make significant inroads with the growing number of blue-collar Republicans, he may be able to cause the polished and affluent Romney some anxious moments--even if the odds are now strongly in the latter's favor. "Usually, you win hearts and the head follows," said longtime New Hampshire GOP activist Tom Rath, who is supporting Romney. "This may be a time when we win heads and the hearts will follow. Diana Ross was right: 'You can't hurry love.' "

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