Amid the so-called ‘refugee crisis’, South European cities have experienced far-reaching societal transformations, magnified by flaws in multi-level governance. How can urban actors cope with such critical questions, which affect their communities and yet lie beyond their full jurisdiction? This article contends that left-leaning governments and ideologically sympathetic social-movement activists at the city-level are incentivised to join their forces. Alliance-building is a strategy to secure political gains while shaping policies within an otherwise unreceptive, hostile context. This argument is built by intersecting multiple scholarly contributions and illustrated through a comparison of pro-migrant policies in the cities of Milan and Barcelona.