As Donald Trump edges nearer to being the Republican Party's presidential nominee in 2016, there is a lot of talk about the possibility of a Republican Party split, or an overall realignment of the party. These are terms with which political scientists and political historians are familiar, but the concept may not be well understood beyond the lecture hall, and many politically aware Americans aren't cognizant of recent realignments because it's an event that doesn't occur very often. However, we can understand Trump's soaring popularity more fully with some perspective on what may be happening to our political parties.
First, political parties are the enduring institution that our democracy uses to organize voters, candidates, elected officials, and activists into coalitions. Our electoral rules more or less guarantee that the US will nearly always have only two dominant parties, because we elect only one person to each legislative district. This means that our parties will always be loose coalitions, "big tents," or broad umbrellas that typically include strange bedfellows. Such is the nature of coalition building.
Party realignment occurs when the group of people (voters, activists, etc.) who associate with a particular party label fragments, such that the coalition that forms each party is made up of a different group of people. Some political scientists understand these grand shifts to be rare. We can identify about six different time periods in American history where this has occurred.
But these big shifts do not occur overnight, or even during a single election cycle. Scholars Gary J. Miller and Norman Schofield published a critical paper on this topic in 2003 in the discipline's flagship journal. In this paper the authors use a mathematical model to show that partisan realignment has occurred in a predictable, clockwork fashion.
The following graphic depicts this conceptualization. (All models oversimplify things in order to be instructive, so forgive the lack of nuance here.) Economic liberals are those who tend to support government redistribution of wealth or income, while economic conservatives oppose economic redistribution of wealth or income. The social dimension in American politics is often thought of as a race dimension, where liberals favor government support for racial minorities and conservatives oppose such policies.
This two-dimensional space provides four quadrants that help us categorize our politics. In the dark blue liberal quadrant we would find people like Jimmy Carter and Al Gore. In the opposing dark red conservative quadrant we would find Ronald Reagan and both Presidents Bush. The upper right quadrant can be thought of as "cosmopolitans" who favor big business but also support government efforts toward racial equality (e.g., Arnold Schwarzenegger). The lower left quadrant includes the populists who are anti-big business and opposed to government support for racial minorities (e.g., Pat Buchanan or George Wallace).
Thinking about where the political parties, and their major candidates, align in this space helps us to identify the dividing lines in American politics. Back in the 1960s and '70s the cleavage line was pretty close to that y-axis, where Democrats were somewhere on the left side of the economic dimension and Republicans were somewhere on the right side.
Miller and Schofield show that the party that loses an election has a strong incentive to try to peel away voters from the winning party. This is how a party grows its coalition to win in the next round. The party does this by taking policy positions that appeal to voters who may only weakly identify with the winning party. Think of these voters as the ones at the edges of the cleavage lines.
Hans Noel demonstrates that political parties are born out of a complicated, market-style competition for ideas that originate in political ideologies. If ideologies are the pure forms of political ideas, then parties are the attempt to apply those ideas and turn them into policy proposals. Moreover, Noel shows that during the George W. Bush and Obama years we have experienced near parity between ideology and party identification. In other words, liberals align with Democrats and conservatives align with Republicans. This is represented on the graph (largely adopted from Miller and Schofield) by the 1996 cleavage line, where the dark blue circle is on one side and the dark red circle on another.
Miller and Schofield show that this cleavage line rather naturally rotates in a clockwise fashion across time. Bill Clinton broke up the previous partisan alignment when he proposed more conservative economic policies, like those of the cosmopolitans, moving the Democratic coalition from the liberal position more to the cosmopolitan one.
George W. Bush was arguably more economically liberal than Ronald Reagan if we consider his expansion of Medicare and his "compassionate conservatism" theme, which may have helped the Republican coalition move closer to the populist circle.
In the 2016 election we see strong evidence of Donald Trump capturing voters who used to vote Democratic but who now are drawn to the Trump campaign. Trump is pretty squarely in the populist quadrant and doing quite well there, which is consistent with the clockwise direction of partisan cleavage movement explained by Miller and Schofield.
More traditional conservatives, like Marco Rubio, and traditional liberals, like Bernie Sanders, have drawn some support but do not appear poised to win their respective party's nominations. If the new cleavage line in American politics has moved from one that separates liberals from conservatives to one that separates populists from cosmopolitans (or is at least shifting that way) then Sanders and Rubio's losses make sense; they're not maximizing the most voters they can along the dominant dimension.
This also suggests that we should expect Hillary Clinton to, perhaps over time, look more pro-big business and less pro-blue collar. Assuming Sanders's campaign is unsuccessful, it's unclear if those who strongly support wealth redistribution would move to Clinton or to Trump. The model here suggests Trump, but the campaign rhetoric from Clinton is trying to attract these voters.
Party realignment isn't so much rare as it is glacial. Parties are constantly reorganizing themselves to build winning coalitions. Some elections make the evidence of this sloth-like reorganization of politics more apparent, and 2016 appears to be one of those. The model here suggests that our politics will continue to evolve in this direction; recall that over the course of 100 years after the American Civil War the ideological positions of Democrats exchanged full-fold with Republicans (i.e., the party that freed the slaves does not have the same label as the party that championed civil rights). Fortunately, we can use political science models to help us better understand why this is happening and what it means for our politics moving forward.
Scott D. McClurg, a professor of political science at Southern Illinois University at Carbondale, contributed to the content of this post.