Populism, radicalism, and protest mobilization by parties in Europe

As European democracies struggle with a ‘crisis of representation’, populist parties appear to be instrumental in channeling popular discontent with governments across the continent, including through protests. While contemporary theories propose a strong connection between populism and protest mobilization, this has seldom been tested in a comparative perspective. At the same time, research has found that radical parties are more likely to mobilize for protests, and those parties are often also populist. We empirically disentangle these relationships with a comprehensive dataset of 4.8 million Facebook posts by all active sitting MPs in all EU27 national parliaments plus the UK between 2018 and 2023, using large language models to identify protest-related posts and those that announce protest events. Findings show that it is particularly radical parties mobilizing their followers, with populism itself having little additional explanatory power. This is the first cross-national, longitudinal evaluation of a much-touted theoretical connection between populist parties and protest mobilization, finding that it appears smaller and more conditional than prior research proposed.