The safest prediction one can make about this year’s congressional elections is that the voters who decide them will look very different from the ones who settled the 2012 presidential contest. The share of minorities and, especially, young people in the electorate will almost certainly decline; the proportion of whites and, especially, seniors will increase.
This shift isn’t new. Midterm elections have long attracted fewer voters than elections in presidential years have, with minorities and young people among the groups most likely to stay home. In the five presidential elections from 1992 through 2008, exit polls conducted for a consortium of media outlets found that voters under 30 cast, on average, 18 percent of the ballots; in the five midterms that immediately followed those elections, young people accounted for just 12 percent of the votes. Voters over 65, by contrast, increased their share of the vote from 15 percent to 19 percent. The decline among minorities hasn’t been as consistent or as severe, but their share of the vote dropped two percentage points from 2004 to 2006, and three from 2008 to 2010, which are big shifts as these things go.
But while the voting falloff between presidential-year and midterm elections has remained constant, its impact has been vastly magnified by a racial and generational realignment that has remade each party’s base of support since the 1980s. In presidential and congressional races alike, Democrats today fare best among minorities, Millennials, and white voters (especially women) who are single or college-educated. Even in a country rapidly growing more diverse, Republicans still rely almost entirely on whites, running best among those who are older, blue-collar, married, rural, and male. In other words, Democrats have become increasingly reliant on precisely the groups most likely to sit out midterms, while Republicans score best among those most likely to show up.