Radical right behavior and support for radical right parties have increased across many countries in recent decades. A growing body of research has argued that, similar to the spread of other extremist behaviors, this is due to an erosion of political norms. This suggests that re-stigmatizing radical right parties might be an effective way of countering their growth. We use a survey experiment in Spain that compares the effectiveness of three theory-driven interventions aimed at increasing political stigma against a radical right party. Contrary to expectations, we fail to validate the efficacy of vignette-based attempts at stigmatization, instead identifying some backlash effects. Methodologically, our findings underscore the importance of validating treatments, as we show that simple attempts at re-stigmatization can produce null or opposing effects to their intended purpose. Theoretically, our results support the idea that normalization is a “one-way street,” in that re-stigmatizing parties is difficult after a party has become normalized.