In Steering the Senate, Gerald Gamm and Steven S. Smith fill a longstanding void in the congressional literature. While political scientists have devoted a tremendous amount of attention to leadership in the US House of Representatives, next to nothing has been done on Senate leaders. Gamm and Smith address this inequality with a tour-de-force treatment of the historical development of leadership institutions in the upper chamber. Even though the House and the Senate are part of the same body, they are remarkably different in the developmental paths their leadership institutions have followed, with the Senate’s trajectory presenting formidable challenges to the formal rule-based institutional approach that has dominated research on Congress over the past several decades. Formal rules and procedures have always seemed to play less of a role in the Senate relative to the House, and this is especially true with its leadership, where the constitutionally designated presiding officers (the vice president and the president pro tempore) have never served in any way remotely similar in scope and power to the Speaker of the House. Why the chambers did not experience parallel development in this regard is one of the central puzzles addressed in the book.

Gamm and Smith develop a theory to explain the evolution of leadership in the Senate, focusing on how inter-party competition drives legislative party development, with entrepreneurial senators taking advantage of opportunities when fellow partisans are open to accepting organizational changes. Those opportunities tend to arise when the chamber is evenly divided in terms of seat shares, increasing the incentives to innovate to make it easier to hold coalitions together to produce a favorable party label in the eyes of the electorate by advancing the party’s agenda over the opposition of the other party. In short, partisan competition in the electoral arena and within the chamber incentivizes entrepreneurial senators to create new institutional features that enhance their ability—along with that of their fellow partisans—to win on policy and with voters.

To test their theory, Gamm and Smith engaged in a Herculean effort to collect and digest an enormous trove of newspaper articles to inform their discussion. As the project progressed, the authors and their research team took full advantage of advances in the digitization of historical newspapers, vastly improving their ability to systematically gather and analyze information about the evolution of Senate organization by those reporting on it in real time. The result is a rich account of Senate battles and the personalities that fought them, all framed in terms of a set of theoretical considerations designed to wrest coherence from complexity. Merely providing the historical details extracted from these original sources (in particular by offering an inventory of the Senate’s leadership positions and those who occupied them) would already have been an important contribution to the literature. The fact that Gamm and Smith do so through a detailed theoretical framework elevates this to a major work that is essential reading for anyone interested in how Congress operates, both in the present as well as the past.

Although the institutionalization of the upper chamber’s leadership was a drawn-out affair, we learn that change was not gradual, with major structural innovations occurring at different key points in Senate history. During the mid-nineteenth century, nascent party caucuses emerged as devices for promoting senators’ policy goals, with caucus chairs playing central roles in managing legislative business. As the Senate moved into the final decades of the nineteenth century, steering committees took over party management functions, including the responsibility for building policy coalitions. In the 1890s to early 1900s, the foundation for the modern Senate leader was laid when Arthur Pue Gorman acted as the entrepreneur by taking on floor management and party spokesperson roles, first in opposition as a member of the minority party to thwart the goals of the leaders on the Republican side. By the 1910s, floor leaders were recognized for both the majority and minority parties, with the majority leader adding to their set of responsibilities that of serving as the intermediary between the Senate party and the president.

The book also sheds light on important procedural developments in the Senate, including the use of unanimous consent agreements and the establishment of the right of first recognition in 1937, which means the majority leader is recognized by the presiding officer before any other senators. Seen today as possibly the most important procedural tool available to the majority leader, its beginnings were quite humble: the right of first recognition was established simply via a statement from the presiding officer (then-Vice President John Nance Garner). While important procedural innovations have been established by rulings from the chair (in some cases, the vice president), this right did not follow that route and did not even involve a vote by the full Senate to establish its legitimacy, as is usually the case for the establishment of precedents of this magnitude. This development, along with the relatively informal way that leadership roles accrued, raises questions about the extent to which these institutional features themselves are imposing constraints on senators’ behavior or are merely reflecting equilibrium patterns of behavior.

The book largely sidesteps this question and others related to the trade-offs that senators make when accepting institutional arrangements that require them to cede procedural prerogatives to party leaders. Yet given the partisan focus of the book’s central theoretical argument, it is important to grapple with the issue of how institutions can remain stable when there is the temptation to change them to prevent policy outcomes that are not favored by a coalition with the votes needed to produce institutional change, as Keith Krehbiel explored in his 2004 article in Journal of Economic Perspectives. Presumably, senators favor the efficiency of having a central coordinating mechanism for legislative business. But if these institutional arrangements involve agenda-setting power where some items are given priority over others—and especially in extreme cases, certain items are not granted any floor time—this raises concerns about how the mechanism and the attendant powers granted to party leaders can be maintained. This takes on heightened urgency in a place like the Senate, where so much is done informally, and what is believed to be one of the most important procedural rights is simply asserted and has not been established through any formal process (and thus may present opportunities for arbitrary and capricious use).

The Senate, as much as any political body, blurs the lines between what constitutes its formal institutional structure and what are mere patterns of behavior, as Daniel Diermeier and Krehbiel argue in their 2003 article for the Journal of Theoretical Politics. But even with the broad prerogatives that individual senators have long enjoyed—and that could lead to procedural chaos—senators appear to have found self-reinforcing equilibrium outcomes with respect to leadership that have helped to maintain the status of what is undoubtedly the most powerful upper chamber in the world. At first glance, the story of Senate leadership spun by Gamm and Smith appears to be consistent with formal work that demonstrates how risk-averse legislators would be willing to accept policy bias introduced by asymmetric procedures in exchange for a reduction in procedural uncertainty. (For this formal analysis, see Diermeier, Carlo Prato, and Razvan Vlaicu’s 2015 work in the American Journal of Political Science on “Procedural Choice in Majoritarian Organizations.”) A deeper, more systematic assessment of this dynamic in the Senate is most welcome, and fortunately, Gamm and Smith have provided a profoundly rich historical account to propel this conversation forward.