‘Tweets, Posts, and Plots’: Political Parties & Conspiracy Theories on Twitter and Facebook Across Four Countries

What if post-truth politics is driven by political elites rather than citizens? This paper examines the extent to which political elites disseminate conspiratorial content on social media. Using a new coding framework, we systematically capture and analyse the conspiratorial messages in 76,688 social media posts from politicians on X and Facebook across four countries—Belgium, Finland, Greece, and Poland. Our findings reveal that radical and populist parties are significantly more likely than mainstream parties to spread conspiracy theories, regardless of their role in government or opposition. We also find that right-wing parties spread more conspiratorial posts than left-wing parties and, Eurosceptic parties are twice as likely as pro-European parties. Conspiratorial posts also tend to rise during election periods. Taken together, our findings reveal how political parties use conspiratorial messaging online, reshaping our understanding of their role in post-truth politics.