Rewrite Sovereignty referendums entail no major change in the electoral support of both the winning and losing sides, according to a study by UPF this news headline for the science magazine post

 there a relationship between the outcome of a sovereignty referendum and the subsequent electoral performance of the political parties? Is a sovereignty referendum associated with an increase in electoral support among winners and a decrease among losers? These questions, which have lacked attention in research until now, have been answered in an article published recently in the journal Party Politics, involving Toni Rodon, associate professor in the Department of Political and Social Sciences at UPF; Nikandros Ioannidis, holder of a PhD in Political and Social Sciences from UPF and currently associated with the Cyprus University of Technology (CUT); and Marc Guinjoan, lecturer in the Department of Political Science and Public Law at the Universitat Autònoma de Barcelona (UAB) and former lecturer at the UOC.

“Our analyses indicate that sovereignty referendums on average have a non-significant relationship with subsequent election outcomes”

The study conducted by the three authors indicates no substantial relationship between winning a sovereignty referendum and the electoral outcomes of the parties in the elections. It also shows that referendums do not affect the territorial position of the parties, regardless of the referendum outcome. According to the authors, “our analyses indicate that sovereignty referendums on average have a non-significant relationship with subsequent election outcomes.”

Certain nuances when the referendum outcome is close, when the opposition wins and in EU referendums

Despite the overall lack of a relationship, the authors did observe certain relevant nuances in this pattern: “The main party in the winner’s block loses electoral support when the referendum is decided by a small margin, especially if they are the leading party in the winner’s block.” Furthermore, “when the opposition wins a sovereignty referendum, its subsequent electoral performance marginally improves,” they indicate. In addition, the authors conclude that winning or losing a sovereignty referendum does not serve as a triggering factor for a political party to change its territorial policy model for one that is more moderate or radical.

With regards to European Union (EU) membership referendums, when the position of anti-EU parties wins, the authors observed that these formations become less Eurosceptic. “Our analysis suggests that anti-EU referendum winners in EU referendums are more likely to leave behind some of their anti-EU positions –and hence become slightly more Europhile,” they explain.

The study is based on a publicly available dataset (CONREF) created by the researchers, with support from the Institute for Self-Government Studies (IEA). It includes information on 77 referendums held in 32 countries between 1956 and 2020, as well as the electoral outcomes of the parties –over 500 political formations– before and after the referendum, their political position in several key areas and other indicators commonly used in the literature on party politics and referendums.

What factors may influence these outcomes?

According to Rodon, Guinjoan and Ioannidis, this lack of a clear relationship between referendum results, electoral outcomes and the political position of the parties may be due to several factors.

“It could be that referendums essentially constitute a ‘signalling tool’ that allows some actors to show the breakdown in the bargaining process between the different actors. In other words, they are seen as a tool in the middle of the journey and not at the end of it,” they argue.

Another interpretation is that “sovereignty referendums mainly occur in places where preferences are stable and very much ingrained in people’s minds. Therefore, even if some changes take place among some voters after the referendum, the aggregate change is small.”

According to the authors, the results of their research “contradict the idea that sovereignty may be used as a strategic tool to radicalise political demands on the issue at stake.”

Cited paper: Rodon, T., Guinjoan, M., I Ioannidis, N. (February 2025). “Electoral and partisan consequences of sovereignty referendum outcomes: A comparative analysis”, Party Politics