A close relationship with a Social Democratic party has traditionally been regarded as one of the best strategies unions have to defend workers’ interests. This conclusion still seems valid today, since the changes in the economic and social structure in the advanced capitalist societies alter the traditional content of their relationship, not the reason for cooperation. However, this belief assumes among a unitary labor movement. The experience of Southern Europe shows, on the contrary, that, when the union movement is divided according to different partisan preferences, union leaders are forced to choose between their relationship with their parties, or cooperating among themselves and being effective in the labor market. In addition, the divorce between the Spanish Socialist party and the Socialist Union reveals that, no matter how strong these organizations are, and despite their history of close ties, inter-union competition and a growing economy make their relationship even more damaging for the union’s interests.
