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The latest Rasmussen Reports poll of the GOP race shows that Rick Santorum leads Mitt Romney by 12 points, 39 percent to 27 percent. Newt Gingrich and Ron Paul are far behind. In and of itself, that's nothing new. The man from Massachusetts has at times trailed Michele Bachmann, Donald Trump, Chris Christie, Rick Perry, Herman Cain and Newt Gingrich in the polls.

What is new are the numbers from a head-to-head matchup with no other candidates in the race. Santorum leads Romney 55 percent to 34 percent. None of the earlier Romney alternatives could manage better than a toss-up in such a contest.

Those numbers show that Santorum picks up 16 points when other candidates drop out. Romney adds just 7 to his column. Santorum makes huge gains among conservative voters when others drop out of the race. Among non-conservatives, Santorum and Romney gain roughly equal amounts. For the first time, the numbers show that if one of Romney's challengers drops out, the other challenger will overwhelmingly benefit. Gingrich supporters, by a three-to-one margin, would vote for Santorum over Romney if that was the final choice.

Both Romney and Santorum are well-liked by Republican Primary voters, but Santorum has a slight advantage on this pointm as well. Seventy-five percent offer a favorable opinion of Santorum, while 66 percent say the same of Romney

There is a huge passion gap favoring Santorum, though. Forty percent of Republican primary voters have a very favorable opinion of Santorum. Just 18 percent are that enthusiastic about Romney...