After being excluded from the Swedish Social Democrat party in 1917, the Revolutionary Socialists founded the Social Democrat Left Party. From this point onwards, the Social Democratic hegemony and dominant position within the Swedish workers movement and political landscape was challenged. This thesis aims to investigate the power struggles between these two parties, the Revolutionary Socialists and the Social Democrats, and their desire to influence control of the unions. Taking cues from earlier research calling for a more localized look at this struggle, this thesis turns to a case study of union matters of the the Factory Workers Union Local 84, at Västerviks Tändsticksfabrik, a match manufacturer and largest employer in the Swedish coastal town of Västervik from 1925 to 1930. Organizational material including meeting protocols, annual reports and member registration lists from the local political parties, cooperative union organizations (VFS) and Local 84 serve as secondary data sources. These documents were then analyzed through the methodological and theoretical framework of power resources. The findings from this study were extensive. However, first and foremost, the results show Local 84 to be dominated by members of the Swedish Communist Party (SKP) during the length of the study period. Interestingly, the material also indicates strong collaborative ties between Social Democrats and non-party workers on issues surrounding local condition and everyday issues. The everyday class struggle against the factory owners was very successful for the communist leadership, resulting in broad confidence among the workers, in turn strengthening the communist representative’s positions. Despite the claim that communists tended to resort to more conflict-laden measures, such as strikes or blockades, to achieve their demands, this study presents a different conclusion. The strategy of the communists in Local 84 was instead focused on collaboration beyond political boundaries in order to achieve their local and practical demands.