Summary: The aim of the work is to address the relationship between trade unions and politics on the basis of an analysis of the case of the self-party Lear, an experience of grassroots trade unionalism in Argentina strongly affected by labour conflict. We wonder how politics is expressed in the day-to-day nature of the factory, how work, politics and trade union action are articulated, and to what extent left-wing militancy is seen as an external element (or not) to the working space. To this end, we use a qualitative methodology, based on the analysis of in-depth interviews with delegates and activists from the factory.