Who serves as the presiding officer of the Senate?

The presiding officer of the Senate is the Vice President of the United States. This role is explicitly defined in the Constitution, which designates the Vice President as the official leader of the Senate, although they do not participate in day-to-day legislative proceedings unless their vote is needed to break a tie. The Vice President's primary function in the Senate is to maintain order during sessions and ensure that the rules are followed, facilitating the legislative process.

The other roles mentioned, while significant in their own right, do not serve as the presiding officer in the Senate. The Speaker of the House leads the House of Representatives, not the Senate. The President Pro Tempore is a senior member of the majority party in the Senate, elected to preside over the Senate in the absence of the Vice President, but does not hold the primary role of presiding officer. The Majority Leader, also a vital position, is responsible for leading the majority party in the Senate and steering legislative agendas but does not serve as the presiding officer either.