Looking Back On Partisanship and Party Loyalty Trends During the 2016 Election

One of the most important lessons from the 2016 election was more of a reinforcement of what we already knew: the strength of partisanship in shaping vote choice. More recently entering public life as a powerful force and becoming a veritable social identity, party affiliation has been widely understood as the variable most predictive of vote choice. The trend in this dynamic–self-identifying Democrats voting for Democratic candidates and self-identifying Republicans voting for Republican candidates–has grown over time, but the past election cycle seemed primed to test it on the Republican side. Donald Trump ran a campaign rife with sexist marks that would presumably turn off female voters–specifically the white ones that historically vote largely Republican–and racially insensitivity that would in part cause the flight of more educated whites.

There was some movement toward the Democratic column among these groups in 2016 compared to the 2012 election, but not of the decisive type. Most importantly, Trump still won these groups relative to Clinton support. White women voters went Trump 52-43 (+5 net point Democratic gain relative to 2012), and white college-educated voters voted Trump 49-45 (+10 point Democratic gain). These two cases serve as just microcosms of the broader process at play: party identification continued to govern vote choice–in this case voting for Trump–to a large extent. To display the best current measures of party loyalty voting and specifically the percentage of Republicans voting for Trump that we have right now, as well as contextualize those numbers historically, the below graph shows the party loyalty rate among both parties in elections from 1972 to 2016. All data came from the collection of historical exit poll data from various organizations maintained by the New York Times. One caveat to note: exit polls are not of very high quality data, not least because it doesn’t group Independents with the parties to which they lean (I discussed why doing so is important here). Nevertheless, the data here is still meaningful.

Rates at which partisans vote for their respective party candidates have stayed high but constant among Republicans (with the key exceptions of the 1992 and 1996 elections in which Ross Perot drew Republican votes), but have risen considerably among Democrats. While only 61 percent of Democrats voted for their candidate, George McGovern, in 1972, the loyalty to their own party has grown to a point where the rate hit a peak in 2012, with 92 percent of Democrats voting for Barack Obama.

Of course, in the context of the previous discussion, the critical takeaway here is that partisans stayed very loyal to their parties in during the 2016 election. Most importantly, Trump garnered the support of 90 percent of Republicans, right in line with the loyalty rates his Republican predecessors received.

The path that led to these high, constant loyalty rates did not necessarily go smoothly. As I’ve touched on in the past, there was plenty of movement in intra-party support trends in the months before the election, with Clinton in fact gaining a higher loyalty rate throughout the campaign–though she trailed Trump by one point in this measure in the end according to exit polls. To give a broad overview, the below chart shows both party loyalty and “defection” rates–Clinton/Trump support among both Democrats and Republicans–using all the data that HuffPost Pollster provides on pre-election polling.

Democrats were much more attached to Clinton even in mid-2015 long before she secured the nomination than Republicans were to Trump. That greater party loyalty rate for one’s own candidate remained higher among Democrats essentially throughout the entire campaign. Nevertheless, both Clinton and Trump see their intra-party loyalty rise particularly around the post-party convention periods in August and thereafter. At that same time, defection rates–represented at the bottom of each of the above grids–declined around this same time.

To get a clearer sense of trends in party loyalty and the strength of partisanship in bringing voters back into the partisan fold, the below graph shows the same trend as the above one excepts it narrows down the time frame down to the start of June–around the time when Trump clinched the Republican nomination with Clinton having already sealed hers.

There was never too much of a disparity between party loyalty rates, but one thing becomes very clear: Democrats expressed much higher commitment to their nominee in Clinton than Republicans did for their nominee in Trump at every point in the general election season. Loyalty rates among voters in both parties generally have an upward trajectory, but it’s notable that Trump’s loyalty trend fluctuates a bit more. That likely reveals the effects of his various controversies that caused some Republicans to rescind their Trump support but later “come home” to the party and support Trump. Alternatively, these dips in Trump support could signal moments that Republicans responded to polls less because of unfavorable events for their party’s candidate (i.e. their preferences didn’t change, but their response rates did).

Regardless, the point stands that Clinton enjoyed greater party loyalty in polls throughout the pre-election time frame, but partisans came to their candidates at large rates. To sum up the data on party loyalty rates throughout the campaign, here’s a table that shows the average rates by month for each party and clearly quantifies what the data visualizes in the above graphs.

Source for data: HuffPost Pollster.

After June, Clinton sees greater party loyalty rate the closer the calendar gets to Election Day. At the month level, loyalty rate hit a nadir in August when 80.5 percent of Democrats supported Clinton. Democrats steadily come home to the party thereafter, as in each of the following months more of them express intent to vote for their nominee. That culminates in 87.7 percent of Democrats pledging their vote to Clinton in November before the election (i.e. the average of polls in the final week of the election). On the other side of the aisle, party loyalty fluctuates relatively more for Trump, but his lowest rates occur in the same months that Clinton experienced here: July and August. After gaining more partisans in September and seeing a dropoff in the subsequent month, Trump sees his highest party loyalty rate in November with 84.5 percent of Republicans saying they would vote for him.

It’s worth noting that undecided partisans were included in all of these numbers. The process of these voters coming home to their respective parties increased loyalty rates for both candidates in the end, but when compared to exit poll data–89 percent loyalty rate for Clinton and 90 for Trump–it appears that party loyalty kicked in more for Trump at the ballot box. A comparison between averages of pre-election polls and exit poll data isn’t perfect, but the data suggests that partisanship was a greater force for Trump at the last moments before Election Day. Without these Republicans coming home late in the campaign, Trump likely would not have won the election.

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