The literature on immigration from a political opportunity structure (POS) approach mainly focuses on those institutional and cultural factors that explain the mobilization of immigrants at the national and local levels. However, this literature pays little attention to those factors that explain the emergence of specific alliances under circumstances such as politicized immigration conflicts (PICs) at the local level. Taking as a point of departure the POS debate, I seek to explain why alliances between political parties and immigrant associations emerge in the presence of PICs. I will use the results of a qualitative case-studies research carried out on three conflicts that started in the Catalan cities of Badalona, Lleida and Vic in the years 2010-2011. I argue that alliances between political parties and immigrant associations emerge because of the existing local political environment where the studied conflicts occur. In order to defend the argument stated above, I consider two institutional-related dimensions and two conflict-related dimensions that explain the formation of alliances: the first two are the institutional openness for immigrant associations and the configuration of power. The other two are the conflict frame, this is how political elites frame the PIC; and the ideology behind the position political parties had on the conflict.In the end, it is possible to explain the relevance of these factors in the alliances between actors who interact under the aforementioned circumstances.