“The one thing that is consistent is that Mitt Romney is in the top tier, that Mitt Romney appeals to about one-quarter of all Republicans and that he has built a large, established, experienced, national presidential campaign," said Rothenberg. "Whether that will be enough to get the nomination, we don’t yet know.”

The first test of the 2012 Republican race is less than five weeks away, when voters in the Midwestern state of Iowa hold caucus meetings on January 3 to express their preferences in the eight-candidate Republican field.