Ambassadors are responsible for working with national governments in order to ensure that their national interests are being met. In the United States, Ambassadors are part of the US State Department.
The Senate
The president.
congress
The Congress.
Executive
Cabinet members, the white house chief of staff, supreme court justices
The president appoints federal judges, ambassadors, cabinet members and various "czars".
The President of the U.S.
The Congress.
The US Senate has to confirm the important appointments, such as cabinet members and ambassadors.
Senate?
The President of the United States.