Party members hold a monopoly over leadership selection in most democracies, influencing their parties' ideological trajectories and electoral strategies. Although members—particularly those belonging to youth wings—are often portrayed as more ideologically extreme than party elites, surprisingly little is known about how they balance policy preferences against electoral considerations. Using a conjoint experiment with over 5,000 party and youth wing members in Portugal, I investigate the extent to which members trade off policy congruence for electoral viability in leadership contests. Results reveal a strong overall preference for ideologically closer candidates, even at potential electoral costs; yet members tolerate moderate policy divergences when candidates present clear electoral advantages. Contrary to expectations, youth wing members are not stricter ideological purists compared to their senior counterparts; if anything, they display greater electoral pragmatism. Exploratory analyses suggest that ideological radicalism and issue salience amplify the outweigh of policy congruence, while incentive structures do not condition members' policy-electoral trade-offs. These findings illuminate key micro-foundations of endogenous party change, clarify the nuanced role of members as “ideological watchdogs,” and offer broader implications for spatial competition theories, intra-party democracy, candidate selection, youth in politics, and political representation.