This is the upper house of the legislative branch- at both the national and state levels- where treaties and appointments are approved

The Senate

Explanation:

The U.S. Congress have two houses -- The Senate and the U.S. House of Representatives.

The United States Senate is the Upper House or the Upper Chamber of the United States Congress. whereas the lower house is the U.S. House of Representatives. They together form the bicameral legislature.

Each Senate is elected for a period of 6 years.

The Senate has the power to approve the treatise and the appointments. Here the impeachment trails are held.

Thus the answer is "The Senates"