The office of Senate floor leader is very much a twentieth-century invention. Throughout the Senate's earlier history, actual leadership rested in the hands of adroit committee chairmen, other senior senators, and newer members with previously established political roots.
By 1900, as the nation became a world power, increasing legislative activity placed a new priority on floor-based coordination and agenda-setting. In the new century's first decade, these functions principally rested with four extraordinary senators: Nelson Aldrich of Rhode Island, Orville Platt of Connecticut, John Spooner of Wisconsin, and William Allison of Iowa. Indiana Senator Albert Beveridge found among these four men the qualities expected of modern-day floor leaders. Allison was the "conciliator and adjuster," Spooner the "debater," Platt the "designer and builder," and Aldrich the "manager."
As chief agenda-setter and legislative strategist, Nelson Aldrich was at home both in committee rooms and on the Senate floor. His power derived from his expertise in the major finance-related issues of the day and his coalition-building ability. In 1901 the Baltimore Sun isolated Aldrich's source of strength: "He knows when to 'bluff,' when to bully, when to flatter and when to anger. The man who is lacking in alertness he bluffs, the timid man he bullies, the vain man he flatters, and the man whose judgment is overturned when angry he torments and taunts until he loses his temper and is put at fault."
The crisis of World War I and the battle over its concluding treaty spurred the further evolution of Senate floor leadership until in the 1920s the institution took a form easily recognizable today. In 1927, the Democratic leader began the tradition of sitting at the front-row, center-aisle desk on his party's side of the Senate Chamber. Ten years later, in January 1937, his Republican counterpart took the corresponding desk across the aisle. This placed both leaders in easy view of the presiding officer and led to another major milestone in the Senate leadership's evolution.
On August 13, 1937, Vice President John Nance Garner announced a policy—under the rule requiring the presiding officer to "recognize the Senator who shall first address him"—of giving preferential recognition to the majority and minority leaders. As Senator Robert C. Byrd later quipped, without that essential power, the majority leader "would be like an emperor without clothes."