From a Rasmussen poll released yesterday:

...The new Rasmussen Reports survey of Iowa caucus participants shows Romney on top with 25% of the vote followed by Paul at 20% and former House Speaker Newt Gingrich at 17%. Texas Governor Rick Perry and former Pennsylvania Senator Rick Santorum, both at 10%, are the only other candidates in double-digits.

... This poll reflects the highest level of support yet measured for Romney and Paul. It’s also by far the best result yet for Santorum who on Tuesday received an endorsement from Bob Vander Plaats, a major social conservative leader in Iowa. While the Evangelical Christian vote is very divided at this time, Santorum now picks up 19% of it, more than any other candidate. Romney is close behind at 18%.