The chronicle of European social democracy is often told from the perspective of the party leader. If the party triumphs at the polls, it is surely because the leader is a visionary. If, on the other hand, the party loses elections, weak leaders are held responsible for that misfortune. Clearly, leadership matters but perhaps not in the top-down manner it used to. Drawing on the literature on political leadership and the Europeanisation of public policy, this chapter argues that the collaborative approach to statecraft deployed by the Portuguese Prime Minister António Costa in the period 2015–2019 paved the way for a period of political stability and electoral victory of the Socialist Party. Using the method of process-tracing to analyse official documents, parliamentary debates, and media reports, the chapter shows that collaborative statecraft enabled Costa to get four budgets approved, to complete a four-year mandate while leading a minority government, and to win the elections of 2019. The chapter also shows that the abandonment of collaborative statecraft in the period 2019–2023 resulted in greater political uncertainty and contributed to the socialists’ defeat at the 2024 elections.