Strom Thurmond served as the President Pro Tempore of the Senate which means he was third in line to succeed the President of the United States, following the Vice President and the Speaker of the House. The President Pro Tempore presides over the Senate, or appoints other Senators to preside, when the Vice President is not present. As the Presiding Officer, the President Pro Tempore can recognize members desiring to speak, introduce bills, or offer amendments and motions to bills being debated; decide points of order, subject to appeal to the full Senate; appoint senators to House-Senate conference committees (although it is customary for the presiding officer to take the recommendations of the floor manager of the bill in question); appoint members to special committees; enforce decorum in the chamber and galleries; initiate certain actions when the Senate is acting under cloture procedures; sign enrolled bills; and administers oaths. Among other duties, the President Pro Tempore sits on certain boards and commissions related to broad management of the Capitol; makes appointments to certain commissions and committees; appoints senators to trade delegations; and makes recommendations for candidates to be the Comptroller General of the United States and the head of the Congressional Budget Office.

Senator Thurmond served his first tenure as the President Pro Tempore from 1981-1987. He was considered the most senior Republican when he was elected President Pro Tempore in 1981 even though John Tower of Texas had served longer as a Republican. Thurmond began his Senate service in 1954 as a Democrat, becoming a Republican in 1964; the Republican Conference agreed to base his seniority on the date he entered the Senate, not the date he switched parties. Senator Thurmond began his second tenure as the President Pro Tempore in January, 1995, when he was elected to that position by his colleagues in the Senate Republican Caucus.