Gingrich Surging in South Carolina

Nate Silver unequivocally answers a question he posed yesterday--does Newt Gingrich have momentum in South Carolina?--in his FiveThirtyEight blog post today: "Yes, Mr. Gingrich does have momentum — and a lot of it." He writes, "Six different South Carolina polls have been released so far today, and they show a split in their results." Three of them, automated polls by Rasmussen Reports, Public Policy Polling and InsiderAdvantage, "have Mr. Gingrich in the lead...by margins ranging from 2 points to 6 points."

The polls strongly indicate that Mr. Gingrich's performance at the Monday debate has contributed to his rise in the polls. Marist for NBC News, one of the more traditional polls conducted by live interviewers, "showed Mitt Romney leading by 10 percentage points." But when Marist "split its results," it appeared that the debate did indeed give Mr. Gingrich some momentum with South Carolina voters. Mr. Silver writes, "Mr. Romney’s lead was smaller — 5 points — in the post-debate sample." Further, the aforementioned automated polls that show Mr. Gingrich in the lead "were conducted on Wednesday, after the debate and the qualified endorsement Mr. Gingrich received from Sarah Palin."

The FiveThirtyEight forecast model suggests that Mr. Gingrich is, in fact, gaining significant momentum. According to Mr. Silver, "The model now shows a virtual tie in the race, with Mr. Gingrich projected to get 34 percent of the vote and Mr. Romney 33.6 percent and each candidate having about a 50 percent chance of winning."

Most of Mr. Gingrich's gain, however, does not appear to be connected to a drop in the polls for Mr. Romney. Mr. Silver notes, "Mr. Gingrich has gained ground in the polls more than Mr. Romney has lost it. Two days ago, our forecast had Mr. Gingrich with 22.6 percent of the vote, so he has gained about 11 points since then. Meanwhile, Mr. Romney’s projection has declined less than 3 points — to 33.6 percent from 36.1 percent — over the same interval."

So where is Mr. Gingrich getting his new projected votes? According to Mr. Silver, "Mr. Gingrich’s gains have come from Rick Santorum and Rick Perry (who dropped out of the race today and endorsed Mr. Gingrich), as well as from undecided voters." Mr. Silver does go on to acknowledge that automated polls, because they usually do not call cell phones and "also generally have lower response rates than traditional polls," may not be the best source.

For now, Mr. Silver anticipates that the Saturday primary could yield a number of different results. He writes: "Our research shows that high levels of volatility and disagreement in the polls make polling aggregation methods less reliable. In other words, the margin of error on the forecast is especially high, enough so that either Mr. Romney or Mr. Gingrich could emerge with a clear victory by the time that the vote takes place on Saturday."