How Political Parties Shape Public Opinion in the Real World

After the storm on the U.S. Capitol in Washington, D.C., on January 6, 2021, President-elect Joseph R. Biden Jr. noted , “At their best, the words of a president can inspire. At their worst, they can incite.” T he question of how powerful political parties and their leaders are in shaping public opinion has intrigued political scientists since the beginning of systematic empirical research. Yet one obstacle has continued to get in the way of finding systematic answers : In the real world, political parties rarely change their position or messaging on major political issues – and when they do, researchers usually arrive too late to identify any effects on opinion.

In our article, “ How Political Parties Shape Public Opinion in the Real World , ” we present some of the most direct evidence to date of how citizens respond when their party changes its position in the real world on issues with direct concern to citizens’ welfare. We thus focus on party elite influence on citizens’ policy opinions. Moving beyond the sterile experimental setting used by most extant work, w e rely on a rare quasi-experimental panel study of how citizens responded when their political party suddenly reversed its position on two major and salient welfare issues in Denmark. With a five – wave panel survey collected just around these two events, we show that citizens’ policy opinions changed immediately and substantially when their party switched its policy position – even when the new position went against citizens’ previously held views.

Specifically, w e fielded a five-wave panel survey in the aftermath of the Great Recession in Denmark 2010-11, hoping that parties would announce dramatic changes in their position on specific welfare policies. Fortunately for our study, major political parties, including that of the Prime Minister, announced two wide-reaching policy reforms that came as a surprise to political observers: a 50 percent reduction in a widely used unemployment insurance program and, later, the abolition of a popular early retirement program. Hence, in both cases, the stakes were salient and real.

We tracked opinions on the exact policies in question, enabling us to gauge what people thought about the cutbacks before and after their party proposed them. Furthermore, our panel survey closely bracketed the two policy changes – i n one instance with less than two months passing from the pre- to the post-wave – limiting the influence of alternative, co-occurring events. On bot h issues, we find that citizens’ policy opinions immediately moved by around 15 percentage points in response to their party ’ s new issue position compared to similar citizens whose par ty did not change its position.

Importantly , the marked opinion change was not only driven by citizens already (partly) supportive of welfare cutbacks. To the contrary, parties were successful in reversing opinions among their supporters, moving them from opposing cutting down welfare to supporting it. The magnitude of opinion change among citizens is remarkable because it is on par with or even larger than many experimental studies, despite such studies are conducted in clean environments with captive audiences and typically on much less salient policy issues .

In short, our findings suggest that partisan leaders can indeed lead citizens ’ opinions in the real world, even in situations where the stakes were real and the economic consequences tangible.

As we discuss in the article, our findings contribute to understanding the magnitude, duration, homogeneity and underlying psychological processes of party cue effects on citizens’ opinion formation. For example, the large and durable party cue effects in our real-world study suggest that experimental studies might, in fact, tend to underestimate the influence of political parties on public opinion. Likewise , our findings of few and small differences within partisan groups in how citizens responded to parties’ changing policy positions might lead researchers to be more cautious in concluding how heterogeneously citizens respond to party signals . This result , indeed, is further support of our interpretation that partisan elites exert a substantial influence on their supporters.

Like our other recent article in American Journal of Political Science , “ Partisan Elites as Culprits? How Party Cues Shape Partisan Perceptual Gaps , ” this study offers an empirical foundation for normative debates about party elite influence on citizens. Our empirical evidence that p art y elites, at least under some conditions, have the power to directly shape how citizens form political opinions and even interpret the facts at hand leaves partisan elites with a responsibility to administer their influence carefully.

About the Author(s): Rune Slothuus is Professor in the Department of Political Science at Aarhus University and Martin Bisgaard is Assistant Professor in the Department of Political Science at Aarhus University . Their research “ How Political Parties Shape Public Opinion in the Real World is now available in Early View and will appear in a forthcoming issue of the American Journal of Political Science.