Abstract: Traditional political history portrays presidential elections as dramatic events that unified a loose confederation of state parties and frequently decided party control of the national government. In this paper we investigate presidential coattails and the partisan effects of state electoral institutions on Senate elections. We find a strong role for presidential elections under both indirect and direct elections, but one subject to the mediating influence of state electoral laws and institutions. We also find that passage of the 17th amendment further tightened the responsiveness of Senate to presidential elections, and reduced the anti-Democratic bias of indirect elections.