When and why are prime ministers able to fulfil their election promises? Scholars have long theorized, but never tested, that actors who can exploit their own and other parties’ electoral expectations in policy bargaining are better able realize their goals (Lupia & Strom 1995, Becher and Christiansen 2015). However, this expectation remains untested. Previous empirical work on the fulfilment of electoral promises has sidestepped the question of electoral bargaining leverage and focused instead on government attributes. Employing a new measure of coalition inclusion probabilities derived, in part, from party-level polling data in European parliamentary democracies, we offer the first empirical test of this central prediction of legislative bargaining models. Our results show that prime ministers with electoral leverage and the power to threaten early elections realize up to 18 per cent more of their election promises.