While populism is theorized as a rhetorical frame combining anti-elitist and people-centric elements, the relative importance and interaction of these components remain understudied. Despite theoretical predictions about populism’s role in promoting emotional extremity, polarization, and democratic erosion, empirical evidence linking specific rhetorical elements to these outcomes is limited. This paper will advance our understanding through a novel AI-assisted vignette experiment that systematically disentangles the impact of populist rhetoric’s constituent elements. By independently manipulating the presence of anti-elitist and people-centric rhetoric while controlling for other message characteristics, we will assess whether populism’s documented effects stem primarily from anti-elitism, people-centrism, or their interaction. The study will also examine key moderating factors that may condition these effects, including political sophistication and personality. This research will contribute to both theoretical discussions about populism’s nature and empirical understanding of its effects, while demonstrating the utility of AI-assisted experimental methods in political communication research for generating controlled variations in rhetorical frames.