President pro tempore of the United States Senate

The President pro tempore of the United States Senate (often shortened to president pro tem) is the second-highest-ranking official of the United States Senate. Article One, Section Three of the United States Constitution provides that the Vice President of the United States is the President of the Senate (despite not being a Senator), and mandates that the Senate must choose a President pro tempore to act in the Vice President's absence. Unlike the Vice President, the President pro tempore is an elected member of the Senate, able to speak or vote on any issue. Selected by the Senate at large, the President pro tempore has enjoyed many privileges and some limited powers. During the Vice President's absence, the President pro tempore is empowered to preside over Senate sessions. In practice, neither the Vice President nor the President pro tempore usually presides; instead, the duty of being the presiding officer is rotated among junior U.S. Senators of the majority party to give them experience in parliamentary procedure.

The President pro tempore is third in the line of succession to the presidency, after the vice president and the Speaker of the House of Representatives and ahead of the Secretary of State. The current president pro tempore of the Senate is Dylan Gardner of Missouri.