How and When Interest Groups Manage to Sway Public Opinion

Much evidence suggests that interest groups (similar to political parties) not only respond to but also try to shape public opinion. So far, however, we know little about the effectiveness of these attempts. The few studies that test an effect of interest group activities on public opinion come to opposing conclusions and leave many gaps in our understanding of the relationship between interest groups and public opinion. My key expectation is that IGs can affect public opinion, understood as both individuals’ attitudes towards an issue and the salience they attach to this issue. Such an effect may occur via several “mechanisms”. On the one hand, interest groups may provide issue frames that change citizens’ attitudes towards a policy. An issue frame stresses a specific interpretation of an event. On the other hand, lobbying activities may provide a cue to people with little information about a policy. In this paper, I try to figure out how important the two mechanisms are relative to each other. One way of doing so is to systematically vary frame strength and the presence or absence of an interest group cue. The difference in public opinion between the scenario with a weak (strong) frame with interest group cue and a weak (strong) frame without interest group cue captures the cueing effect; and between the scenario with (without) interest group cue and a weak frame and the scenario with (without) interest group cue and a strong frame the framing effect. I rely on survey evidence on the Transatlantic Trade and Investment Partnership to test my expectations. The paper squarely contributes to the following question raised in the workshop programme: “How and through which mechanisms do advocacy groups shape politicization processes through mobilizing and organizing in different policy areas and phases?”