The FiveThirtyEight Team Goes To Iowa

TOLEDO — The Democratic race has mostly been a two-way affair between Hillary Clinton and Bernie Sanders, but the tightening of the polls in Iowa means that the third wheel in this race, Martin O’Malley, is becoming more important. Why? O’Malley is currently at 5.1 percent in our polling average, which is far greater than Clinton’s 1.8 percentage point advantage over Sanders in that same polling average. Iowa Democratic caucus rules dictate that a candidate needs a minimum of 15 percent support at a caucus site to remain viable (some sites have a higher threshold). When a candidate does not reach that percentage, his or her supporters must give their votes to their second choice. Even in FiveThirtyEight’s polls-plus forecast, which gives Clinton a 7.6 percentage point advantage over Sanders because of her overwhelming lead in the endorsement race, O’Malley’s 6.8 percent is nearly equal to Clinton’s lead. Most recent polls have not asked O’Malley supporters whom their second choice would be, but there are some indications that they favor Sanders. That’s why we need to keep an eye on O’Malley, even if he can’t win. His supporters could end up paving the way to a much closer finish than expected.