“Take back control”? The effects of supranational integration on party-system polarization

Abstract

In this paper, we examine the relationship between supranational integration and domestic party-system polarization (extremism). We first construct a theoretical argument that uncovers the key trade-off between the "output legitimacy" of a supranationally integrated party system and the inevitable loss of "input legitimacy" caused by externally imposed policy constraints. This translates into a strategic tradeoff between responsibility and responsiveness at the party level of electoral competition. We hypothesize that while moderate supranational policy constraints can initially speed-up platform convergence, ever-closer political integration may reverse the trend towards higher levels of party-system polarization and party extremism. We apply our framework to the case of EU integration and test our key non-monotonic prediction both at the party-system level of polarization and at the party level of ideological extremism. Finally, we apply to synthetic control method (SCM) for causal inference in comparative case studies to study how political integration and supranational policy constraints have affected their overall level of party-system polarization over time. Our overall empirical analysis strongly corroborates our theoretical argument.

From convergence to congruence: European integration and citizen–elite congruence

“…Second, challenger parties may be more vote-seeking than our argument assumed, thus leading them to adopt less extreme positions and represent moderately non-centrist voters left behind by the convergence of mainstream parties towards the common EU policy. In other words, the effects of the convergence of mainstream parties on congruence may be attenuated by the increase in party-system polarisation due to the rise of challenger parties (Konstantinidis et al, 2019). Third, it is possible that mainstream party convergence is accompanied by similar convergence among the voters, either due to mainstream party cues or because mainstream parties respond to the converging public.…”

Why vote when you cannot choose? EU intervention and political participation in times of constraint

“…As Le Gall (2017) argues, European integration has the effect of both (a) advancing interstate economic dependence and (b) introducing an additional layer of responsibility in the multilevel governance framework. This is theorised to have a negative effect on turnout (Le Gall, 2017), given that devolving sovereignty to the EU and becoming more integrated with the economies of other states reduce the catalogue of policy areas over which state governments can act autonomously and, as a result, reduces the level of partisan competition over a number of issues (Dorussen and Nanou, 2006; Konstantinidis et al., 2019; Nanou and Dorussen, 2013) but particularly over economic policy concerns (Ward et al., 2015). The effect of both the diluted sovereignty of state governments as well as the reduced competition between political alternatives is likely to drive voters to view domestic elections as an inadequate means of shaping policy outcomes (Mair, 2013).…”

National polarization and international agreements

“…Empirical studies using a measure of party polarization similar to that applied in this paper (the distance between party positions) have found that membership of the European Union has been associated with a nonmonotonic evolution of party polarization-initially decreasing and then increasing. Initial entry for a number of member states was associated with a decline in party polarization, but this was later followed by a rise in party polarization in the United Kingdom, Greece, Poland, Austria, Spain, and Portugal as the net benefits of membership declined (11). The explanation for this lies in the increased costs/decreased net benefits of membership.…”

“…For example, changes in the conditions confronted by member states of the European Union (EU) over the last two decades have strained willingness to comply with EU agreements. Nevertheless, only the United Kingdom has opted to withdraw from the Union (10,11). By contrast, while the COVID-19 pandemic might have been expected to generate a coordinated international disease control effort under the World Health Organization, the immediacy of the threat to national populations led to an almost wholly decentralized response to the pandemic (12).…”