Social networks as pathways of political mobility in Portuguese governments

Political mobility in executive appointments is often explained through party affiliation and career trajectories, yet relational embeddedness across institutional arenas may also characterise those who reach ministerial office. We examine, retrospectively and in an exploratory manner, whether the social networks formed by co-participation in Portuguese governmental and parliamentary venues are associated with ministerial appointments. Using web-scraped data on the composition of the Constitutional Governments and the Portuguese Parliament between 2015 and 2024, complemented with the Registers of Interests of government and parliament officials, we construct an individual-venue bipartite network and its projection onto individuals. We estimate the cumulative network of Governments XXI-XXII and, within each policy-domain, retrospectively screen potential candidates for the XXIII Government by ranking actors in the top five positions of at least one centrality measure (betweenness, reach, closeness, weighted closeness, or eigenvector), computed on portfolio-specific subgraphs and restricted to nodes reachable from the Prime Minister. With the identification of 9 out of 16 in-network ministerial appointments, this procedure outperforms both a random selection baseline (mean recall 0.6%) and a career-ladder heuristic based on prior secretarial experience in the same domain (recall 12.5%), consistent with network centrality being informative about the appointment process in stable, well-populated policy-domains. We assess whether Ministers exhibit systematically higher institutional reach than non-ministerial actors using bipartite degree centrality, visualised via a log-scaled KDE, and validated with non-parametric tests (10,000-iteration permutation tests and Mann-Whitney U tests). We decompose connectivity by venue type (e.g., Government, Parliament, Political Party) using a categorical profile comparison and cosine similarity. Ministers display higher bipartite degree centrality than non-ministerial actors (mean 0.0200 vs. 0.0105; difference 0.0096; permutation p-value = 0.021; Mann-Whitney p-value