This paper examines the individual dynamics of sexist attitudes and its consequences for support for the far right. The empirical analysis focuses on the case of Spain, which has recently witnessed a strong wave of feminist mobilization followed by the sudden electoral surge of the radical-right party Vox. We use unique panel survey data tracking individual attitudes of sexism and voting behavior yearly during the same period (2017-2020). Sexist attitudes are measured using the modern sexism scale (Swim et al. 1995), which captures the key dimensions of the Spanish far-right discourse regarding gender, i.e. denial of continued discrimination against women, antagonism towards women’s demands, and lack of support for policies designated to help women. Our paper makes three significant contributions. First, the results of mixed growth models show that levels of sexism change in the short term in a way that is compatible with a within-individual backlash effect. Citizens are seemingly reactive to contextual political events in their levels of sexism. Second, we show that sexism is a key predictor of vote choice for the radical right, outweighing in explanatory power all other sociodemographic and attitudinal predictors (including nativism and nationalism) with the exception of left-right self-identification. Finally, we show that the gender gap in radical right support can be accounted for considering sexism. Overall, our findings provide evidence of the existence of individual-level gender backlash effects, and highlight the importance of sexism as a fundamental individual predictor of far right support.