It was just two weeks ago that Rasmussen Reports released the first Iowa Caucus poll showing Mike Huckabee with an advantage over Mitt Romney. A lot has changed over the past two weeks and Huckabee’s lead has now grown to double digits.

The latest Rasmussen Reports telephone survey of the Iowa caucus finds Huckabee with 39% of the vote, Romney with 23% support, and everyone else in single digits. Rudy Giuliani and Fred Thompson get just 8% of the vote in Iowa at this time. Arizona Senator John McCain is at 6% just one point ahead of Congressman Ron Paul (see crosstabs).

Huckabee’s support in Iowa is up eleven points from the poll conducted in late November. Over the past month, Huckabee has more than doubled his support from 16% on November 12 to 39% today. Romney has lost two points from the previous survey and is down six points over the past month.

Huckabee also leads in South Carolina, is tied for the lead in Michigan, and is near the top with Rudy Giuliani in the Rasmussen Reports daily Presidential Tracking Poll. Results for the latest polling in New Hampshire will be released later this week.

Sixty-two percent (62%) of Evangelical Christians now support Hucakbee in Iowa. That’s up from 48% in the previous poll. Huckabee also leads Romney among other Protestant voters by a 33% to 25% margin.

Huckabee leads by fourteen points among men and by eighteen points among women.

Among those who have participated in the caucuses before, Huckabee attracts 39% support while Romney is at 24%.

Fifty-six percent (56%) of Likely Caucus participants say they are certain they will not change their mind before January 3. That includes 57% of Huckabee supporters and 55% of those who prefer Romney. Twelve percent (12%) of likely caucus participants say there is a good chance they could still change their mind while 29% say they might change their mind. Among those who say there is a good chance they might change their mind, Huckabee is the second choice for 24%, Romney for 21% and Giuliani for 19%.

Overall, Romney and Huckabee are each the second choice for 19% of likely caucus participants. Thompson is the second choice for 16%, Giuliani for 12%.

Among those likely to take part in the Iowa Republican caucuses, 81% now have a favorable opinion of Huckabee. That’s up five points over the past two weeks and sixteen points over the past month. That figure includes 51% with a Very Favorable opinion of Huckabee.

Romney is viewed favorably by 75%, Thompson by 72%, and McCain by 57%. Those figures have changed little over the past two weeks or the past month.

However, just 60% now have a favorable opinion of Giuliani. That’s down from 68% two weeks ago and 74% a month ago.

As for unfavorables, just 16% offer a negative assessment of Huckabee. Twenty-three percent (23%) have an unfavorable opinion of Romney, 24% say the same about Thompson, and 38% have a negative opinion of Giuliani.

Seventy-six percent (76%) of Likely Caucus Participants could identify Romney as the candidate who gave a speech on faith and religion last week. Ninety-four percent (94%) could identify Romney as the candidate who is Mormon. As you would expect, those figures show that Iowa caucus participants show a far higher level of awareness that voters nationwide.

Thirty-two percent (32%) said that a candidates faith and religion is a Very Important factor when considering how to vote. That figure jumps to 54% among Huckabee supporters. Just 18% of Romney supporters share that view.

Sixty-five percent (65%) of Likely Caucus Participants believe the Republicans will win the Presidential Election in 2008. Sixteen percent (16%) think the Democrats will win while 19% are not sure.

All polling for caucus events presents challenges in determining who is likely to show up and participate. In conducting and analyzing this survey, Rasmussen Reports reviewed results for many possible levels of turnout. While the results varied modestly depending upon the turnout model, the overall dynamic was the same in all cases—Huckabee holds a solid lead over Romney and nobody else is close. See information on screening questions and the sample used in this telephone survey.

See survey questions and toplines. Crosstabs available for Premium Members only.