Social media has been an important tool in the expansion of the populist message, and it is thought to have contributed to the electoral success of populist parties in the past decade. This study compares how populist parties advertised on Facebook during the 2019 European Parliamentary election. In particular, we examine commonalities and differences in which audiences they reach and on which issues they focus. By using data from Meta (previously Facebook) Ad Library, we analyze 45k ad campaigns by 39 parties, both populist and mainstream, in Germany, United Kingdom, Italy, Spain, and Poland. While populist parties represent just over 20% of the total expenditure on political ads, they account for 40% of the total impressions$\unicode{x2013}$most of which from Eurosceptic and far-right parties$\unicode{x2013}$thus hinting at a competitive advantage for populist parties on Facebook. We further find that ads posted by populist parties are more likely to reach male audiences, and sometimes much older ones. In terms of issues, populist politicians focus on monetary policy, state bureaucracy and reforms, and security, while the focus on EU and Brexit is on par with non-populist, mainstream parties. However, issue preferences are largely country-specific, thus supporting the view in political science that populism is a "thin ideology", that does not have a universal, coherent policy agenda. This study illustrates the usefulness of publicly available advertising data for monitoring the populist outreach to, and engagement with, millions of potential voters, while outlining the limitations of currently available data.

翻译：社交媒体已成为民粹主义信息传播的重要工具，普遍认为其在过去十年中推动了民粹政党的选举成功。本研究比较了2019年欧洲议会选举期间各民粹政党在Facebook上的广告投放策略，重点考察其目标受众客群与议题聚焦的共性与差异。通过利用Meta（原Facebook）广告图书馆数据，我们分析了德国、英国、意大利、西班牙和波兰39个政党（含民粹与主流政党）的4.5万个广告活动。尽管民粹政党的政治广告支出仅占总量的20%以上，但其广告贡献了40%的总曝光量——其中多数来自疑欧派与极右翼政党——这暗示民粹政党在Facebook上具备竞争优势。我们还发现，民粹政党发布的广告更易触达男性受众，有时也覆盖更年长群体。在议题层面，民粹政客聚焦货币政策、国家官僚体系改革与安全议题，而欧盟与脱欧议题的关注度与民粹-主流政党持平。然而，议题偏好高度呈现国家特异性，这印证了政治学界关于民粹主义是"薄意识形态"的观点——该意识形态缺乏普适性、连贯性的政策议程。本研究揭示了公开广告数据在监测民粹政党触达数百万潜在选民及其互动方面的价值，同时指出了当前可用数据的局限性。