Abstract. In recent decades, support for the far right has surged in many countries. One common explanation for this is that far-right support is a backlash against left-wing governments and their policies. We investigate the causal effect of the partisan make-up of governments on the electoral results of far-right parties. Evidence from over-time comparative data and a quasi-experimental analysis based on a regression discontinuity design in Spain indicates that far-right parties benefit electorally when the current government is on the left. In further analyses, we employ a novel regression discontinuity design (RDD)-based sampling strategy to examine original individual-level survey data from Spanish municipalities close to the discontinuity cutoff. These data show that the likely mechanism underlying the backlash effect is an ideological shift to the right among the electorate when left-wing parties govern. Overall, the far right benefits more when the mainstream left governs than when the mainstream right does.