Seniority in the United States Senate

Seniority in the United States Senate is valuable as it confers a number of benefits and is based on length of continuous service, with ties broken by a series of factors. Customarily, the terms "senior senator" and "junior senator" are used to distinguish the two senators representing a particular state.

The United States Constitution does not mandate differences in rights or power, but Senate rules give more power to senators with more seniority. Generally, senior senators will have more power, especially within their own caucuses. In addition, by custom, senior senators from the president's party control federal patronage appointments in their states.

The president pro tempore of the Senate is traditionally the most senior member of the majority party.

There are several benefits, including the following:

A term does not necessarily coincide with the date the Senate convenes or when the new Senator is sworn in. In the case of Senators first elected in a general election for the upcoming Congress, their terms begin on the first day of the new Congress. Since 1935, that means January 3 of odd-numbered years. The seniority date for an appointed senator is the date of the appointment, not necessarily the date of taking the oath of office. In the case of Senators taking vacant seats in special elections, the term begins on Election Day. However, in both of these cases, if the incoming Senator is a Member of the U.S. House of Representatives at the time, he/she must resign from the House before her/his term in the Senate begins.

A senator's seniority is primarily determined by length of continuous service; for example, a senator who has served for 12 years is more senior than one who has served for 10 years. Because several new senators usually join at the beginning of a new Congress, seniority is determined by prior federal or state government service. These tiebreakers in order are:

When more than one senator has served in the same previous role, length of time in that prior office is used to break the tie. For instance, Richard Shelby and John McCain both took office on January 3, 1987, and each had previously served in the House of Representatives. Shelby, having served 8 years, is more senior than McCain, who served 4.

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