In this paper, I argue that both theoretical and political factors account for this difficult relationship. Theoretically, populism can be intended as a tool to overcome problems of collective action, focusing, in its discourse, on those sectors lacking an own channel of representation. Therefore, populism is likely to attract some constituencies often overlooked by unionism, particularly when the labor market insider-outsider divide is huge. Politically, the existence of strong links between unions and a centre-left party supporting or implementing austerity measures further contributes to the emergence of a delegitimizing discourse against ‘mainstream’ unions.
I focus on the cases of Podemos and Five Star Movement, relying on elite interviews and survey data, in order to describe how these parties, and their voters, assess the behaviour of ‘mainstream’ unions. I argue that a closer look of the Latin American Leftist Populisms contributes to understand several features of the relationship between European Antineoliberal Populisms and the union movement.