This article contributes to the renewal of contextual analyses of electoral behaviour by shedding light on electoral dispositions and political intermediations in two neighbourhoods, one popular, and the other gentrified, of the 18th arrondissement of Paris, in the context of the 2017 presidential and legislative elections. The relational analysis of the mechanisms of production of voting preferences within these very unequal social and ethnic-racial groups who live in close proximity underlines the important role played by collective dynamics of belonging and social class and racial relations in shaping political preferences and affinities. At least as concerns the national elections of 2017, more than instituted mediations within the political field, or even the electoral campaign, primary groups and social and ethno-racial affinities are the prime drivers that explain these groups’ political preferences. Therefore, the main electoral brokerage, both symbolic and practical, is constituted by the way voters define themselves and conceive of social groups, according to markers of social, racial and political domination.