What are the duties of US Senators assigned by the Constitution?

Senators are elected to represent the state from which they are elected. In conjunction with the US House of Representatives they have the authority to pass laws that they deem necessary and proper granted they do not violate the US Constitution. They also, together with the House pass Constitutional Amendments for ratification by the states.

The Senate has powers that are exclusive to that body including: Ratification of Treaties, Consenting to the appointment of Federal Judges, cabinet Secretaries, certain federal officers, and military officers.