How Much Do Labor Unions Influence Elections?

Labor unions have long sought to influence public policy by engaging in various political activities, one of the most prevalent and straightforward strategies being to support specific candidates during elections.

A new paper by University of Chicago’s Alexander Fouirnaies aims to shed light on the relationship between labor union support and electoral success in British parliamentary elections—with staggering results.

“When labor unions supported candidates for Parliament, we found that the candidate’s vote share increased by six percent points, quite a stunning number,” said Fouirnaies. “Their involvement filled campaign coffers, professionalized the candidates’ campaigns, and provided much-needed strategic support which often proved decisive.”

A 1996 revision in the Labour party’s bylaws changed how labor unions were able to support Labour Party candidates, abolishing direct sponsorship of individual parliamentary candidates but providing an incentive for labor unions to contribute to the party organization instead. This change in the bylaws provided an opportunity for researchers to look into the impact that direct sponsorship of candidates had. The study spans from the party's inception in 1900 to the abolition of the sponsorship system in 1996.

One factor that the authors had to control for was inherent candidate quality. “In choosing which candidates to support, the labor unions probably pay attention to the candidates’ charisma, their star power,” Fouirnaies said. “That is why we can't just compare the candidates who got sponsorship to the candidates who didn't, because that would basically be baking in the innate quality of the candidates, and we don't want to do that.

“We want to try to isolate that from the effect of sponsorship,” he continued, “which is why we track the same individual over time and then observe what happens to the performance of the same individual once that person gets the sponsorship deal, relative to all the other candidates that didn't get the sponsorship deal.”

Controlling for candidate quality, union sponsorship still significantly influenced electoral outcomes in the 20th century—usually contributing about six percentage points to their sponsored candidate’s final vote share. This electoral advantage highlights the substantial impact of union support on candidates' electoral success. Union sponsorship not only resulted in votes, but it also significantly professionalized political campaigns, the study shows, with campaign expenditures on paid staff and campaign managers significantly increasing after an endorsement, indicating a shift towards more structured and strategic campaign operations.

The impact of union sponsorship varied based on factors like campaign spending limits and constituency demographics. Sponsorship was most effective when spending limits were less restrictive. Furthermore, union-sponsored candidates were more likely to take advantage of a feature of election law in the United Kingdom which allows candidates to secure nominations in safer constituencies (rather than being required to run in the districts in which they reside).

While the electoral impact of union sponsorship showed consistency across different decades, its influence appeared to wane somewhat from the 1970s onwards. This trend suggests changing dynamics in political campaigning and possibly shifting voter perceptions regarding endorsements and organizational support.

 “These findings shed new light on the role of unions in British politics and may further our understanding of the electoral influence of interest groups more generally,” Fouirnaies said.

The study suggests that the ability of interest groups to influence elections varies significantly depending on electoral rules and financial dynamics, with campaign strategy–and an ability to take advantage of lax regulations–greatly affecting outcomes.

In contexts where strict residency rules for candidates limit the ability of a candidate to choose their voters, for instance, interest groups might still wield electoral influence through a more professionalized campaign apparatus and sophisticated campaign strategy, but without a key tool to success. In countries without spending limits, like the United States, however, campaign donations could play an even more crucial role than observed in the British context, which limits spending.

“An interesting question that I think hasn't really been addressed much in the literature is the extent to which interest groups can influence elections, largely because there are so many interest groups that are operating that it becomes difficult to determine the effects of a particular group,” Fouirnaies said. “Our research suggests that this effect could be significant.”