Huckabee has support among 24 percent of those interviewed for an ABC News/Washington Post telephone poll of 400 Iowa adults considered likely to participate in the caucuses on Jan. 3.
The poll was conducted Nov. 14-18, and had a margin of sampling error of plus or minus 5 percentage points.
Romney was in the lead with 28 percent, followed by Huckabee, and then former Tennessee senator Fred Thompson at 15 percent.
Former New York City mayor Rudy Giuliani garnered 13 percent.
In Iowa, Huckabee leads Romney by about 2-1 among evangelical voters, a pivotal group among likely caucus goers.
Half of Huckabee's supporters say they are very enthusiastic about him, nearly double the fervor shown by Romney's backers.
While Huckabee gets high marks for honesty and handling social issues, his rivals score higher for experience, leadership, having the best chance to defeat the Democrat next November, and issues including Iraq, the economy and immigration.
Associated Press contributed to this story.