The Des Moines Register on Saturday night published more details from the paper's poll of Iowa's likely Republican caucus-goers, including results for all questions asked, a candidate-by-candidate breakdown and "what-if" analysis of various turnout scenarios by Register pollster J. Ann Selzer.

The initial vote preference results, published earlier in the evening, showed Mitt Romney and Ron Paul leading with 24 percent and 22 percent respectively, followed by Rick Santorum at 15 percent. The survey results were based on interviews conducted from Tuesday through Friday this past week.

However, responses from the last two nights of interviewing showed great momentum for Santorum, who rose to second place (with 21 percent) and ahead of Paul (with 18 percent), while Romney's 24-percent support remained unchanged.

Selzer's what-if analysis further demonstrates the potential for volatility and surprise in Tuesday's vote. For example, two very plausible alternative assumptions about turnout yield two very different outcomes:

  • Her sample found fewer evangelicals among likely caucus-goers than in past caucuses, but if she weighted the final two days of interviewing so that evangelicals are 60 percent of participants -- the level reported by network entrance polls in 2008 -- Santorum would lead Romney by five points (25 to 20 percent).
  • Consistent with her previous Iowa polls this year, Selzer found indications of lower turnout among seniors compared to past Republican caucuses. However, if seniors were weighted up to 27 percent of the respondent pool interviewed on the last two days (to match the 2008 entrance poll), Romney would lead Santorum by seven points (26 percent to 19 percent).

Read Selzer's full analysis here.

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