The UN Security Council is deciding which of the six candidates for Kofi Annan's job it will recommend to the General Assembly, for when he steps down at the end of the year. But what makes a good secretary general?
Annan has made good use of his "bully pulpit," say analysts
When Norwegian Trygve Halvdan Lie went to New York to become the first UN secretary general in 1946, expectations were low.
The UN's founders saw the job as essentially bureaucratic, to be filled by a "good chap" who would run the place smoothly.
But this role has changed significantly over time.
"Without any loss of responsibilities, other responsibilities have crept in - among which, one could describe as acting as the world's conscience," says Professor Adam Roberts, the leading academic expert on the UN.
Prof Roberts believes this role began with Dag Hammarskjold, the second Secretary General, who led the organisation during the most intense times of the Cold War, in the 1950s and early 1960s.
Finding the role intensely frustrating - he upset the Soviet Union so much that Nikita Khrushchev called for the role to be abolished - Hammarskjold found himself thinking of things the UN could try and do.
In particular, Roberts credits him with playing a "very creative role" in assisting the development of UN peacekeeping.
But the end of the Cold War changed everything - or at least it seemed at the time.
The UN Security Council found itself ready to fulfil its founding ideals. Following action taken against Iraq for invading Kuwait in 1991, the UN soon found it was engaged in peacekeeping missions around the globe.
Russia's Khrushchev called for the post to be abolished
But Sir Marrack Goulding, one of the top officials during the time, says it was a period of missed opportunities.
"The member states did not respond to the demand created by the end of the Cold War, and we were incredibly stretched," he recalls.
"We didn't get the staff we needed, and as a result some pretty awful disasters took place - in Bosnia, Somalia, Rwanda."
Lord Hannay, Britain's ambassador to the UN from 1990 to 1995, says member states are "ruthless" at manipulating the UN.
"They go about blaming the UN for things that are actually their responsibility - but they go far too far in acquitting themselves," he adds.
Managing the US
There is no doubt secretaries general have been used as a punchbag from time to time by the member states.
The most high-profile victim was the Egyptian, Boutros Boutros Ghali, who, in December 1996, was effectively removed from his post by the Clinton administration after falling out with the Americans over a range of issues.
UN SECRETARIES GENERAL
Kofi Annan, Ghana: 1997-
Boutros Boutros Ghali, Egypt: 1992-1996
Javier Perez de Cuellar, Peru: 1982-1991
Kurt Waldheim, Austria: 1971-1981
U Thant, Burma: 1961-1971
Dag Hammarskj÷ld, Sweden: 1953-1961
Trygve Lie, Norway: 1946-1952
He is, to date, the only secretary general not to have served two terms in the post.
James Rubin, a senior American diplomat at the time, believes the lesson is that any secretary general must get on with the US to succeed.
"Managing the United States is the single indispensable of being an effective secretary general," he says.
"It doesn't mean agreeing with the United States, but it does mean managing the United States.
"It's also true that the United States does not happen to be very popular in the world right now. Since the UN is made up of member states, and most of those member states now do not happen to be very pleased with US foreign policy, you have to be able to manage this great power, but also do it in a way that doesn't make the majority of your members feel as if you're buckling under all the time."
Sir Marrack says any secretary general has to satisfy 192 member states - each with differing visions of the world.
"The member states are not united - on almost any major issue you will see one group of member states arguing with another group of member states," he points out.
"When that happens, the secretariat is in a hugely difficult position. Who are they going to obey?"
To be a success, a secretary general clearly must be strong as well as diplomatic.
But with so many restrictions, can the post-holder expect to make any difference?
"This is not a position of power; this is not a man who can lay down the law," says Sir Marrack.
"But he does have huge influence, and he has a 'bully pulpit'. He can tell the world that they really have to get to grips with whatever it might be - Aids, the environment. Kofi Annan in particular has made a great deal of that influence.
"I think we shouldn't understate the importance of the role. If you put into it someone who couldn't communicate properly, you'd be missing a lot of tricks."
As the member states prepare to choose the eighth secretary general, James Rubin says it is time for people around the world to lower their expectations.
"If major countries in the world aren't prepared to do something, the UN isn't going to be able to do it either," he says.
"If people understood that, they would be less disappointed by the chief diplomat of the United Nations."
But the fact remains that so much hope continues to be invested - a challenge for anyone's stamina, diplomatic skills, and courage.