Swedish political parties are characterized by their markedly different support across geographical space. In most cases, the sources of these regional variations date back to the time of the founding of the parties. Moreover, the regional strongholds and the areas of weak support for the parties have survived major societal changes such as the transition from the agrarian to the industrial society, emigration, and urbanization. Why is it that a certain area evolves a political tradition that sets it apart from neighboring areas? This study addresses itself to this and similar topics with empirical emphasis on the Swedish Social Democratic Party (the SAP).The study is based on the conviction that the regional imbalance in the SAP vote originates in the interaction/competition between various social and political movements in the local environment. The initial model used to explain these imbalances comprises three different factors that influence the party's vote: the socio-economic structure, the local organizational environment and the effect of local party organizational efforts.In order to test the importance of these factors three different areas were selected; one strong, one weak, and one unstable in terms of the Social Democratic vote.The findings show that no single factor alone accounts for the variance in the regional support of the SAP. Rather, what is decisive are the interactions within the structural and social properties of a context.By way of conclusion, this study lends support to the following conclusions of the prospects for the SAP to mobilize the electorate: to establish itself in the local setting the party needs an organizational culture, a local party organization and the absence of strong local opinion against the party's activities and organizational efforts. The party also seems to be favored by a high level of political mobilization (participation), whereas there is nothing to suggest that the SAP's prospects of becoming successful are hampered by competition from the left-wing parties. / digitalisering@umu