Freshman Senators of the majority party are most often tapped to do the duties of the Chair. As has long been the tradition, Senators serve in the chair for approximately one hour at a time. The presiding officer in the Senate is addressed as "Mr. President" or "Madame President," reflecting the fact that the Constitution bestows presiding duties in the office known as President of the Senate.

The Constitution provides that, in the absence of the President of the Senate [the Vice President], the President pro tempore [PPT] will preside. However, the PPT, an elected position, is almost always the most senior majority party Senator and therefore usually a committee chairman as well, and quite busy. In his absence, the Senate tradition evolved of putting junior Senators in the Chair in order for them to better learn the procedures of their new home -- and because more senior Senators don't want the job!

Under the "power-sharing" agreement negotiated by Democratic Leader Tom Daschle [D-SD] and Republican Leader Trent Lott [R-MS] at the start of the 107th Congress, the presiding officer position alternated between the two parties. The change in practice was a reflection of the even split between the parties at the start of the 107th Senate: 50 Republicans and 50 Democrats. Indications are that this practice will continue under the leadership of the new Democratic Majority Leader, Senator Daschle.

Alternating between the sides had been the Senate's normal practice, until 1977. Then Majority Leader Robert Byrd [D-WV] ended the practice, due to an earlier episode when the earlier Majority Leader, Mike Mansfield [D-MT], had been overlooked for recognition by the Republican Senator in the Chair. The majority party has held the Chair ever since 1977 under that precedent, with the exception of the power-sharing period.

Beyond enforcing decorum, answering parliamentary inquiries and ruling on points of order [all carried out under the close watch and with the advice of the Senate's Parliamentarian], the chair has only minimal power over the chamber. His/her advice can be ignored, and rulings overturned by a simple majority vote of the Senate; the Senate's rules state that certain points of order [i.e. those involving questions of constitutionality] must be put to the Senate for a vote and not even ruled upon by the chair; and recognition of Senators on the floor must follow strict Senate protocols: the majority leader, first; the minority leader, second; the committee chairman of the bill on the floor, third; and the ranking minority committee member, fourth.

With so little discretion, the job of presiding is not a popular one among Senators with busy, fragmented schedules.