The Impact of Moderate Voters on the 2014 Midterms

Over the past two election cycles, we have analyzed competitive Senate elections to estimate the percent of moderates a Democratic candidate will need to garner in order to win their race.* The sheer number of moderates required to prevail always illustrates a simple truth: Democrats need moderate voters significantly more than do Republicans, because of the lopsided number of conservatives in the electorate versus liberals. In October 2014, we modeled competitive Senate elections in this cycle based upon historic exit poll data. Now we have the 2014 exit poll data for these states and can match our model to who actually turned out at the polls. The chart below tracks our initial estimate from October and an updated estimate applying the actual ideological breakdown of the electorate from the 2014 exit polls. Only two Democratic candidates garnered the margins they needed among moderates, and they were the only two to win their races (pending final outcomes in Alaska and Louisiana). There is no doubt that moderate voters were crucial to the outcome in 2014, and though Democrats won them 53% to 44% overall, it wasn't sufficient (in fact, they did 2 points worse with moderates than in the 2010 wave).

We make our predictions by modeling the likely ideological composition of the electorate from an analysis of prior exit poll data. Then we assume that 85% of liberals and 15% of conservatives will support Democrats, while 15% of liberals and 85% of conservatives will support Republicans, an approximation which is consistently reflected across most elections. Under these parameters, we estimate how many moderates a candidate needs in order to reach a majority of voters.