Drawing on substantial original interviews and fieldwork data from Argentina's marginalized urban areas, Poverty Shaping Politics reveals how the spatial segregation of slums and vulnerable neighborhoods compels the poor to seek out local political brokers to access resources, while politicians depend on these brokers to navigate poor areas and garner political support. Rodrigo Zarazaga uniquely demonstrates that the establishment of broker networks is driven more by the conditions of segregated poverty and vulnerability than by the inherent capabilities of 'machine-like' parties. Using the case of Cambiemos challenging Peronism in poor districts, Zarazaga provides the first account of a party building broker networks to contest a dominant machine party. While existing literature suggests that sustained economic development can weaken machine parties, this book shows that entrenched and widespread poverty can also threaten their hegemony.