Replication Data for: Comparing ‘responsible party government’ in the US and the UK

Responsible parties are conventionally defined as those capable of announcing their legislative goals and then passing them on the strength of their own members’ votes. In this paper, I consider why UK majority parties have closely approximated these conditions for responsibility since the 1880s, while US majority parties have never approximated them closely. I provide the first systematic evidence on when the British opposition began to offer across-the-board opposition to the government’s agenda and when the government became able to pass bills using only its own members’ votes. I also explore the role that leaders’ control of the legislative agenda and their followers’ nominations played in these developments. I attribute US parties’ inability to mimic their British counterparts to different costs of defending bill passage coalitions against “weakest-link” attacks.