In this paper, we investigate how political parties employ group appeals as a strategic component of negative campaigning in their communication on social media. Although the existing literature extensively explores negative campaigning, it has paid limited attention to the mechanisms that drive specific target choices. One critical and under-researched dimension of this phenomenon is the role of group appeals—messages referencing social groups like social classes, ethnic communities, or occupational groups. Group appeals are a particularly powerful tool for parties to frame political discussions because they tap into voters’ social identities and other group-based predispositions. Through their ability to resonate with voters on a personal level, these appeals can significantly shape how voters perceive political actors and issues. By integrating group appeals into negative campaigning, parties can more effectively highlight their opponents’ failures to represent certain groups while bolstering their own connection to that group at the same time. We therefore expect that parties are more likely to attack their competitors with appeals to social groups for which they have a poor reputation of representation to strategically alienate group supporters and identifiers from their competitors. To test this theoretical expectation, we analyze Facebook and Twitter posts from political parties in the United Kingdom, focusing on the period from 2016 to 2023, and combine this data with public opinion data from the British Election Study Internet Panel. This approach enables us to systematically examine how parties leverage group-based messaging in negative campaigning to shape electoral narratives and voter perceptions.