This book is the first comprehensive study of Senate majority leadership--it covers the office and its occupants from the first incumbent, John W Kern in 1913, through the term of William H. Frist in 2006. Data are both qualitative and quantitative. They include materials from archives of several majority leaders-Lyndon Johnson, Mike Mansfield, Howard Baker, and George Mitchell. Also available are statistics of roll call votes, which reveal continuing patterns of legislative behavior, e.g., leaders seem to be drawn from among senators who are "middle-men" in political ideology but who drift toward more extreme positions depending on the size of their partisan majority. This partisanship, however, is tempered by commitments to institutional loyalty. Research further highlights the continuity of majority leadership in the Senate by noting a path dependent relationship between majority leaders and presidents, who depend on leaders to shepherd their proposals. In their relationship to their states, leaders also are found to be attentive to demands for distributive benefits. All told, these multiple constituencies-state, party, Senate, and president-constrain majority leadership in the Senate. The task of the leader is to balance constraints. In this unprecedented work, Andrea Hatcher examines Senate majority leadership in terms of the constituencies, both electoral and functional, of the Senate majority leader. These constituencies-state, party, Senate, and president-are found to represent constraints on the Senate majority leader as their demands often compete, and the ways in which Senate majority leaders balance them form the contours of Senate majority leadership. It might seem obvious for there to be much variance as Senate majority leaders and their constituents change over time, and, to be sure, differences in leadership styles emerge. However, what is more striking is not the change but the continuity that guides the institutional development of Senate majority leadership. The path dependence is one of constrained Senate majority leadership, not for the conventional wisdom that the majority leader operates in a supermajoritarian institution, but for the broader reason that these plethora of intra-, inter-, and extra-institutional forces pull at the leader. The scope of inquiry is comprehensive, beginning with an identification of trends in the selection of senators to become majority leader. It, then, traces the voting behavior of Senate majority leaders, analyzing by way of statistical findings how the leader represents his party constituency by roll call voting. One key, but often overlooked, variable that this study examines is size of a leader's majority.