The Institutional and Political Architecture of Hostility: How Democratic Regimes and Party System Types Shape Elites’ Hostile Rhetoric

Recent scholarships have stressed the importance of distinguishing between forms of political hostility that are compatible with democracy and those that undermine it, introducing a normative threshold between agonistic and antagonistic communication styles. While the scholarship has increasingly examined the different types of hostility (Papacharissi 2004; Muddiman 2017; Rossini 2020), we still lack the systematic institutional and political explanations for cross-national variation in these rhetorical styles (Walter 2021; Nai 2021).  In this wake, this paper investigates the structural conditions under which political leaders’ communication is more likely to adopt agonistic rather than antagonistic rhetoric. Our theoretical framework covers two sets of macro-level factors - institutional regimes and party-system configurations – that shape leaders’ propensity to foster agonistic or antagonistic communication. First, building on comparative analyses of institutional design (Bernaerts, Blanckaert & Caluwaerts 2023), we argue that consensus-oriented democracies reduce the incentives for antagonist rhetoric by fostering cooperative norms and power-sharing expectations. Majoritarian systems, by contrast, amplify zero-sum competition and political elites are more prone to evolve into antagonist political styles (Gidron, Adams, Horne, 2019). Second, in proportional based representative democracies, characteristics of party systems such as multipartyism, electoral threat structures, and government vs. opposition status, create varying strategic incentives for either confrontational or moderating tones (Mendoza, Nai and Bos, 2024). In this respect, traditional parties may mimic more radical styles (Valentim, Dinas, Ziblatt, 2025) under pressure from challengers (Meguid 2005), while competitive uncertainty can increase the appeal of polarizing communication. We empirically examine these relationships using the Twitter Parliamentary Database, which offers a comprehensive longitudinal and cross-national corpus of politicians’ communication in 18 countries from September 2017 to October 2019. We use social media data (Twitter/X) as a ‘most likely case’ for identifying antagonist rhetoric, due to its features to foster angry, polarizing and even violent discourses (Ryan 2012; vander Goot et al. 2025). By applying a fine-tuned BERT model, we classify tweets according to their hostile rhetoric types (agonistic or antagonistic). We then model how institutional regimes and party-system characteristics condition the probability that leaders employ different polarizing styles during electoral campaigns. Overall, the paper offers a theory-driven and empirically grounded account of how institutional democratic regimes and party systems features shape the rhetorical boundaries of political competition in developing negative rhetoric and its impact on the quality of democracy (Costa, 2025).   Walter, Annemarie S, ed. Political Incivility in the Parliamentary, Electoral and Media Arena: Crossing Boundaries. London: Routledge, 2021. Nai, Alessandro. “Fear and Loathing in Populist Campaigns? Comparing the Communication Style of Populists and Non-Populists in Elections Worldwide.” Journal of Political Marketing 20, no. 2 (2021): 219–250. Papacharissi, Zizi. “Democracy Online: Civility,: Politeness, and the Democratic Potential of Online Political Discussion Groups.” New Media & Society 6, no. 2 (2004): 259–283. Rossini, Patrícia. “Beyond Incivility: Understanding Patterns of Uncivil and Intolerant Discourse in Online Political Talk.” Communication Research 49, no. 3 (2020): 399–425. Ryan, Timothy J. “What Makes Us Click? Demonstrating Incentives for Angry Discourse with DigitalAge Field Experiments.” Journal of Politics 74, no. 4 (2012): 1138–1152.