Morris Fiorina's claim that polarization in the United States is limited to what he refers to as the political class -- a group made up of elected officials and a small set of activists -- is far from the consensus view among political scientists who study public opinion and voting behavior. In addition to myself, a number of prominent scholars have presented evidence in recent years documenting the rise of polarization within the American electorate and the close connection between elite polarization and mass polarization.
Fiorina argues that Americans have become better sorted by party in recent years but not more polarized. He acknowledges that there is a stronger relationship between party affiliation on the one hand and ideology and policy preferences on the other, but he claims that this is different from polarization, which involves a shift in opinion away from the center and toward the extremes. In fact, however, survey data shows that sorting and polarization are two sides of the same phenomenon. As Americans have become better sorted by party, they have also become more polarized. Thus, evidence from the American National Election Studies show that the percentage of voters who place themselves in the center of a seven-point liberal-conservative scale has decreased, while the percentage who place themselves near the left and right ends of the scale has increased considerably since the 1970s.
Perhaps the clearest evidence for growing mass polarization is the growing consistency of opinions across issues and between issues and party affiliation. As a result, the electorate includes much larger proportions of consistent liberals and conservatives than it did 30 or 40 years ago and the ideological divide between Democratic and Republican voters has widened considerably.
Political elites have clearly played a major role in the rise of partisan polarization over the past several decades. But the public, especially the politically engaged segment of the public, has also become much more divided over time. And the divisions within the public have reached the point where they are now constraining the actions of political elites. One cannot understand the deep partisan divide in Washington and many of our state capitols today without taking into account the deep divisions in the nation -- divisions of race, culture, ideology, and geography. For example, there are far more deep-red and deep-blue states now than there were 30 or 40 years ago. In the 2012 presidential election, only four states were decided by a margin of less than five percentage points, while 27 were decided by a margin of at least 15 percentage points, including several of the most populous states.
Perhaps the most significant divide within the electorate today is race, because it underlies many of the other divisions. In 2012, Barack Obama lost the white vote by 20 percentage points, according to the national exit poll, but he won the election by a fairly comfortable margin because he swept the nonwhite vote by a margin of more than 60 percentage points.
As the American electorate has become more racially diverse, the racial divide between the Democratic and Republican parties has widened considerably and this trend is likely to continue for the foreseeable future. The Democratic Party today depends heavily on votes from African-Americans, Hispanics, and other nonwhites. About 45 percent of Democratic presidential and congressional voters in 2012 were nonwhite, compared with only 11 percent of Republican voters. And the growing dependence of the Democratic Party on nonwhite voters, who generally hold much more liberal views on the role and size of government than white voters, has helped to drive racially and economically conservative whites toward the Republican Party, thereby deepening the ideological divide between the parties.
Democrats and Republicans in Washington are deeply divided over a wide range of issues, from the role and size of government to climate change to gay marriage. But those divisions do not reflect a failure of representation, as Fiorina claims. Rather, they reflect accurate representation of very divergent constituencies. And that is why it is going to be so difficult to resolve those differences.