The Presient pro tempore of the Senate is the second-highest-ranking official of the United States Senate and the highest-ranking senator. The Vice President of the United States is the President of the Senate ex officio, and thus is the highest-ranking official of the Senate; during his absence, the President pro tempore is the highest-ranking official in the Senate and may preside over its sessions. The President pro tempore is elected by the Senate; by custom, the President pro tempore is the most senior senator in the majority party. Normally, neither the Vice President of the United States nor the President pro tempore presides; instead, the mundane duty is generally delegated to junior senators of the majority party. The President pro tempore is third in the line of succession to the Presidency, after the Vice President of the United States and the Speaker of the House of Representatives.