Labor Unionization and Social Democratic Parties

The relationship between social democratic parties and labor unions is of interest for the entire era of labor mobilization since the nineteenth century. The middle-class shift in the employment structure of West European countries, the emergence of second-dimension politics, and the pluralization and fragmentation of the “left field” raise several questions in this regard: Have the constituencies of left parties and trade unions developed in parallel or they diverged? Consequently, do the average preferences of trade union members and left voters align or diverge? Do unionized left voters sort increasingly into radical left, social democratic or green and left-libertarian parties? In this chapter, we address the subject of union–party relations and how it relates to social democratic fortunes with microlevel data on membership, political preference profiles, and electoral behavior. We find that the bond between labor unionists and social democrats is anchored in a rather close similarity and convergence of policy preferences. This proximity of beliefs is not limited to questions of economic redistribution but also covers policy issues concerning societal governance and immigration. In many instances, unionists are – on average – more libertarian on questions pertaining to the dimension of societal governance and more inclusive and universalistic on questions of citizenship than nonunionized social democratic voters. In consequence, unionists are progressively less an uncontested electoral preserve of Social Democracy.