Recent scholarly work has shed new light on the erosion of the antiprejudice norm (that is, an understanding that anti-immigrant bias is socially inappropriate and undesirable). However, our understanding of the factors that keep this norm in place, particularly in current times of increasing immigration and rise of far-right actors, is more limited. This study examines factors that sustain the antiprejudice norm within the native population in European countries, focusing on the following research questions: What determines people’s intrinsic commitment to this norm? How socially prevalent do people think the norm is? And what role do these factors play in how political speech might promote tolerance? The paper theorises, first, that individual-level ideology and socio-demographic characteristics (in particular, gender and education) will correlate with natives’ internalised motivation to follow the norm, so that this motivation should be higher among women, highly educated individuals and left-wing voters. Ideology is also expected to explain variation in people’s perceptions of how widespread the norm is in society (social cues). In particular, radical right voters are expected to be likelier to perceive that the antiprejudice norm is socially widespread. Second, this paper proposes that both intrinsic (internalised norm) and extrinsic motivations (sensitivity to the above-mentioned social cues) will moderate the effect of pro-immigration political discourse on public opinion about immigration. Empirically, the paper draws on an original online survey, fielded in Spain, with a vignette-style survey experiment embedded. Among the empirical tests, treatment effect heterogeneity and causal moderation analyses elucidate to what extent intrinsic motivations and perceptions of social cues moderate the impact of pro-immigration speech on mass tolerance. The results have important implications for our understanding of the social and political conditions that inform the persistence of key democratic norms of tolerance and inclusion.