With the Iowa Caucuses now one week away Donald Trump is currently the leader in the race for the Republican Party nomination according to a new computer model that takes into account current polling and endorsements for the major candidates. An algorithm designed to weight both the polls and the endorsements received by the major candidates gives Trump a 44.2 percent chance of winning the Republican primary, compared to 29.9 percent for Ted Cruz and 25.9 percent for Marco Rubio. The algorithm takes into account polls released from a variety of sources, including a new polls of the Iowa Caucus and New Hampshire Primary released yesterday by Fox News and CBS News/YouGov.
The algorithm works by giving a certain weight to a number of factors in calculating the odds that each candidate will eventually win the Republican Party nomination. The heaviest weight, 30 percent, is given to the New Hampshire primary, which has tended to be the most predictive contest over the last 20 years. Other factors included are polling of the Iowa Caucus (20 percent), South Carolina primary (10 percent), and nationwide polling (20 percent). Finally, to account for the effect of the party establishment and super delegates a 20 percent weight is given to the number of endorsements candidates have received using FiveThirtyEight’s measurement of official endorsements for each candidate.
At this time only Donald Trump, Ted Cruz, and Marco Rubio are included in the calculations, as all other candidates are polling too low in Iowa, New Hampshire, and the general electorate to be considered a serious threat for the nomination. Ben Carson has dropped out of the calculations due to his decline poll numbers across the board, virtually eliminating any possibility of him winning the nomination.
So what do the polls say?
A Real Clear Politics average of five New Hampshire primary polls gives Trump the lead with 32.2 percent support. Ted Cruz comes in second with 12.6 percent of the vote, and John Kasich places third with 12.0 percent support. Cruz is surging in Iowa, with some polls now putting him ahead of Trump. However, often the winner of Iowa ends up failing to win the Republican Party nomination. In 2012 Rick Santorum won Iowa and in 2008 it was Mike Huckabee. Both men were eventually overcome by the winners of the New Hampshire primary, Mitt Romney in 2012 and John McCain in 2008. Unless challengers can chip into Trump’s lead in New Hampshire over the next two months there is a good chance he will win the state, and with that victory carry a great deal of momentum into South Carolina and Super Tuesday. Trump’s lead in New Hampshire in the number one reason for his lead in the overall primary forecast.
The Real Clear Politics average of polls in Iowa currently has Trump as the leader with 32.2 percent support, compared to 27.0 percent for Cruz, and 12.2 percent for Marco Rubio. After Cruz surged in Iowa in early January Donald Trump fought back and took the lead in a number of polls released over the last week. The race there is now neck-and-neck between Trump and Cruz. If Cruz can win Iowa he will likely gain a bump in the nationwide polling. Cruz is unlikely to win New Hampshire given the current state of polling there, but a victory in Iowa could enable Cruz to win South Carolina and then potentially carry that momentum into Super Tuesday to compete with Trump. A Trump loss in Iowa could hurt his reputation as the Republican frontrunner.
The Real Clear Politics average of nationwide polling currently has Trump as the dominant force with 34.6 percent support, compared to 18.8 percent for Cruz and 11.2 percent for Rubio. Trump has undoubtedly benefited from the tremendous amount of free media coverage he has received over the last two months and it shows in the current state of nationwide polling. At this time, Trump and Cruz have clearly distinguished themselves from the field nationally. Marco Rubio will need to gain national coverage in the coming two months to make up the gap on Cruz and Trump, which only increases the importance of New Hampshire for Rubio.
Finally, the reason Marco Rubio still has a decent chance is the party establishment factor. As documented at FiveThirtyEight.com, citing a study done by four prominent political scientists, significant endorsements from members of the party tend to cause success in primary states. In previous elections the party elites tended to favor one candidate ahead of the Iowa Caucus and New Hampshire primary, and that candidate tended, with few exceptions, to go on to win the party nomination. Using Silver’s measurement of endorsements, which gives more weight to endorsements from U.S. Senators and state governors than U.S. Representatives, Marco Rubio currently leads the endorsement race among the top three contenders with 43 endorsement points. Coming in second is Ted Cruz with 17 points. Donald Trump currently has no endorsement points..
Some may be surprised that Trump is not even more of a favorite to win the Republican Party nomination given his lead in all three polling areas, and his dominant lead in nationwide polling.
The reason Trump is not even more of a favorite at this point is that polling tends to fluctuate wildly in the months before and after the Iowa Caucus in early February. As Nate Silver of FiveThirtyEight points out, many voters still are not paying attention to the 2016 presidential race, and may change their mind in the coming months. Indeed, exit polls from previous elections show that many voters in the Iowa Caucus and New Hampshire primary likely have still not made up their mind on the candidate of their choice. In early January of 2012 Newt Gingrich was leading nationwide polling of Republican voters, and in 2008 the leader at this point was Rudy Giuliana. Victories in Iowa and New Hampshire tend to change the narrative and give new candidates free and favorable media coverage which can change the nationwide polling numbers dramatically. For all these reasons other candidates, including Rubio, are still given a good chance of overtaking Trump in the coming months.
As the campaign goes on the polling numbers, particularly those in Iowa in New Hampshire, will take on more weight. Right now when putting in the numbers and weighting each contest to the best of our knowledge Trump is the favorite, but other candidates still have more than a fair chance to grab the Republican Party’s presidential nomination.