who is the president of the senate and when may that person vote
The President of the Senate in the United States is the Vice President of the United States. The Vice President holds this title automatically under Article I, Section 3 of the U.S. Constitution and is the Senate’s presiding officer. The Vice President’s main role in the Senate is limited: they usually do not debate or vote on ordinary bills the way senators do. Their most important power is the ability to cast a tie‑breaking vote when the chamber is deadlocked 50–50 on a question. In other words, the President of the Senate may vote only when the Senate is equally divided , and that single vote decides the outcome of the matter before the Senate.
In practice, this means the Vice President often stays out of daily Senate proceedings and appears when a close vote is expected, especially on big nominations or controversial legislation where the parties are evenly split. When the Vice President is absent, a different officer (the president pro tempore or another senator designated to preside) chairs the session, but those officers do not gain an extra tie‑breaking vote; only the Vice President, as President of the Senate, has that specific constitutional power to break a tie.