The Secretary-General was envisioned by U.S. President Franklin D. Roosevelt as a "world moderator", but the vague definition provided by the United Nations Charter left much room for interpretation. The Secretary-General is the "chief administrative officer" of the UN (Article 97) "in all meetings of the General Assembly, of the Security Council, of the Economic and Social Council and the Trusteeship Council, and shall perform other functions as are entrusted to him by these organs" (Article 98). They are also responsible for making an annual report to the General Assembly. They may notify the Security Council on matters which "in their opinion may threaten the maintenance of international peace and security".
Other than these few guidelines, little else is dictated by the Charter. Interpretation of the Charter has varied between Secretaries-General, with some being much more active than others.
The Secretary-General, along with the Secretariat, is given the prerogative to exhibit no allegiance to any state but to only the United Nations organization; decisions must be made without regard to the state of origin.
The Secretary-General is highly dependent upon the support of the member states of the UN. Although the Secretary-General may place any item on the provisional agenda of the Security Council, much of their mediation work takes place behind the scenes.
In the early 1960s, Soviet First Secretary Nikita Khrushchev led an effort to abolish the Secretary-General position. The numerical superiority of the Western powers combined with the one state, one vote system meant that the Secretary-General would come from one of them, and would potentially be sympathetic towards the West. Khrushchev proposed to replace the Secretary-General with a three-person directorate (a "troika"): one member from the West, one from the Eastern Bloc, and one from the Non-Aligned powers. This idea failed because the neutral powers failed to back the Soviet proposal.