On Thursday Mitt Romney fell below 50 percent likelihood to attain the Republican nomination for the first time since Oct. 3.
The chart shows the likelihood of attaining the nomination for the four leading candidates since Thanksgiving morning. A slight downward trend for Romney turned into a downward slide directly following Sunday's Union Leader endorsement of Newt Gingrich, shown with the purple line:
Gingrich is in increasing control of Iowa, where he is 59.0 percent likely to win to Romney's 16.7 percent likelihood, and South Carolina, where he is 58.4 percent likely to win to Romney's 25.5 percent likelihood.
Florida is the most hotly contested state between the two frontrunners. A recent poll has Gingrich 21 points ahead of Romney, but a single poll is a volatile data source in a primary election. The prediction markets give Gingrich 53 percent to Romney's 40 percent, which is the closest of the early primary contests.
Yet, Romney is still the most likely Republican nominee; he is heavily favored to win New Hampshire, where he is 68.7 percent likely to win to Gingrich's 17.5 percent likelihood, and Nevada, where he is 62.0 percent likely to win to Gingrich's 25.0 percent likelihood. While the likely outcomes of the other three early primary contests have shifted quickly with the national polls, these two states remain strongly committed to Romney.
One interesting aspect of the movement in the primary race this week has been the relative lack of major events in the campaign. For once the story is not the stumble of a candidate, but a candidate's relative competence and consequent staying power. The longer Gingrich can maintain his position, the more he will consolidate the anyone-but-Romney faction of the Republican electorate and the greater his likelihood of attaining the Republican nomination for president.
David Rothschild is an economist at Yahoo! Research. He has a Ph.D. in applied economics from the Wharton School of Business at the University of Pennsylvania. His dissertation is in creating aggregated forecasts from individual-level information. Follow him on Twitter @DavMicRot and email him at firstname.lastname@example.org.