The FiveThirtyEight Team Goes To Iowa

CEDAR FALLS — As we make our way to Donald Trump’s event here, I’m reflecting on the conventional wisdom that Iowa is Ted Cruz’s to lose. The FiveThirtyEight forecasts, however, reveal that Trump may have a better chance of winning Iowa than he’s getting credit for. Using only Iowa polls, our forecast gives both Cruz and Trump a 42 percent chance of winning. Marco Rubio has a 9 percent chance, followed by Ben Carson at 4 percent and Jeb Bush at 1 percent. This shouldn’t be too surprising given that Cruz and Trump are each polling at 27.3 percent in Iowa, on average, while no candidate other than Rubio (at 13.2 percent) is polling above 10 percent. Trump’s chance of winning does drop to 28 percent when looking at our “polls-plus” forecast, which takes into account state polls, national polls and endorsements. The reason is that Trump has no endorsements from any governors or members of Congress, and he is doing worse in Iowa polls than in national surveys. Whether or not endorsements actually matter this year isn’t clear. Either way, Trump isn’t so far behind Cruz, who has a 49 percent chance of winning in the polls-plus forecast. If endorsements do matter, that could be good news for Rubio, who is at 18 percent in the polls-plus forecast. No other candidate has more than a 2 percent chance of winning in that forecast. However you slice it, Iowa is either a two-way race or a three-way race with less than three weeks to go.