Social Sorting and Political Cleavages: Evidence from 2.5 Million Electoral Candidates

How socially distinct are competing political parties' candidate pools? Since names encode cultural milieu, lineage, linguistic origin, and ancestry that standard socioeconomic variables miss, we measure social sorting across parties with names, predicting affiliation out of sample within municipality-years. Across more than 2.5 million local-election candidates, names pick the right-wing candidate in a random within-municipality pair 55.8% of the time in Spain and 56.5% in France. Given names alone do most of the work: around 55.0%. Under a stylized model of intergenerational transmission of political orientation, this translates to an implied gap of about 25 p.p. in parental naming propensities. The signal is stable in Spain but doubles in France by 2026. Within ideological families, names separate parties as sharply as across the right-left divide, even more so in France. The Spanish cleavage is linguistic and growing. The French one runs through names of immigrant origin and is strongest in large cities.