Alan Abramowitz, an Emory University political scientist, has published a predictive model of presidential elections for decades. Through three simple factors—economic growth, presidential job approval, and tenure of the incumbent party—Abramowitz explains most of the variation in presidential elections. This time around, his model points to a narrow Republican victory, but he does not believe this result—because the GOP has gotten behind Donald Trump, which “violates a basic assumption of the model that parties nominate mainstream candidates.” Meanwhile, the FiveThirtyEight “polls plus” model, which combines polling and economic data, finds Hillary Clinton nearly a 2:1 favorite over Trump.

Admittedly, the 2016 race is still in flux. Clinton’s standing in the national polls notably declined after FBI Director James Comey excoriated her over her email server. There is a chance Trump could win. Still, all things considered, this is a race that the Republicansshould win, or it should be a virtual toss-up, at least—if it weren’t for Trump.