This paper brings empirical insights into the discussion on politics-administration dichotomy in the context of policy implementation at the local level. Recent research has argued that the design and delivery of public policy is becoming increasingly politicised, often with negative consequences for policy implementation. This is particularly the case where the policy-making capacity and experience of public administration is limited, e.g. in sub-national administrations in Central and Eastern Europe. The contention is that in these contexts, political actors can influence the process of policy implementation and that strategic policy aims can be undermined by short-term, political agendas. Taking the case of EU Cohesion Policy (CP), this paper explores how political and administrative factors interact in policy implementation. The research analyses the implementation of a CP instrument dedicated to functional urban areas (Integrated Territorial Investments - ITI) in two Polish regions. CP funding is an important source of investment in Polish regions and locales and ITI is designed to mobilise cooperation across municipalities. Based on participatory observation, expert interviews and qualitative content analysis of policy documents, the research identifies arenas at different stages of policy implementation where political and administrative rationales interact, and highlights the formal and informal rules that govern this. The paper discusses implications for the P-A Dichotomy, suggesting that in reality the two spheres are constantly interacting in a ‘purple zone’. Rather than a dichotomy, drawing on the Institutional Collective Action framework, the paper delineates formal and informal rules ensuring that this inevitable interaction supports strategic policy implementation.