How do parties use political advertising in election campaigns? Examining issue competition in advertising campaigns on Facebook and Instagram for the 2021 federal election in Germany.

We examine how political parties use advertising on Facebook and Instagram to compete over policy issues in the 2021 German federal election. Using data from the Meta Ad Library, we apply a semi-supervised topic model to examine how parties’ issue attention differs between parties and over time. We find that most parties focus on owned issues in their advertising campaigns, but also engage in rival parties’ issues to larger degrees than expected. The extent to which parties emphasize owned issues throughout the campaign is related to ideological positions, targeting sophistication, and the roles social media played in overall campaign strategies. [ABSTRACT FROM AUTHOR]