<p>Populist parties are characterized by a discourse that pits ordinary citizens against a corrupt elite. This rhetoric increasingly targets not only politicians but also scientists and scientific knowledge. Because citizens often use party cues to form their own opinions, this raises the question to what extent populist parties fuel science skepticism among their supporters. This study examines this question by analyzing 15 annual waves of representative panel data from the Netherlands (2007–2022; <i>N</i> = 19084). Cross-lagged models reveal that the intention to vote for a populist party predicts increased political discontent one year later as much as vice versa. Political discontent, in turn, predicts science skepticism. In addition to this indirect effect, populist voting also increases science skepticism directly. These effects exist both at the between-person level and within individuals, which provides more stringent evidence for causality. This reinforcing spiral provides an explanation for the growing politicization of science.</p>