Abstract
Social democratic parties have undergone a transformative ideological and electoral shift. But how has this affected their alliance with trade unions in terms of personal ties? This article hypothesises that Social democratic parties appoint fewer union-linked ministers as they become more economically centrist and less dependent on working-class voters. However, institutions that stabilise party–union relations should moderate these effects (statutory linkages, high union density, or union involvement in policymaking). Data on 2,600 ministerial appointments in Western Europe show that there is no direct relationship between trade unionist appointments and changes in party electorates or party ideology. However, electoral change is correlated with appointment patterns when institutional stabilisers are weak. Thus, social democrats weaken their elite ties to unions in response to the middle-class shift in their electorates, but only when the institutional context is unfavourable for the party-union relationship.