The vice president of the United States is the first heir to the president of the United States. When the current American president becomes vacant, the vice president will succeed him as the new American president. According to the relevant provisions of the US Constitution, the vice president also serves as the "Speaker of the US Senate". Under normal circumstances, it has no voting right in the Senate. Only when the voting result of the Senate 100 members is a draw, the vice president's vote has the actual decision, that is, the key vote.