The UN Security Council recommends a candidate and the 192-member General Assembly approves the choice. Following are six leading candidates:
BAN KI-MOON, SOUTH KOREASouth Korea's Minister of Foreign Affairs and Trade. He has emerged as a front-runner in the race to succeed Kofi Annan. In an informal straw poll held in July among the 15 members of the UN Security Council, he came out top.
ASHRAF GHANI AHMADZAI, AFGHANISTAN:
Ashraf Ghani, a former finance minister in the Afghan government, is an expert on the economies of developing nations and post-conflict reconstruction.
PRINCE ZEID AL-HUSSEIN, JORDANPrince Zeid al-Hussein, Jordan's UN ambassador, is a widely respected diplomat. If chosen to succeed Kofi Annan, the 42-year-old former UN peacekeeper and cousin of King Abdullah II would be the first Muslim to head the world body.
SURAKIART SATHIRATHAI, THAILANDThailand's Deputy Prime Minister Surakiart Sathirathai has the official backing of all 10 nations in Asia's regional bloc, the Association of Southeast Asian Nations (Asean).
SHASHI THAROOR, INDIAIndia's Shashi Tharoor is a career UN diplomat, having worked in the world body for nearly three decades. The 50-year-old under secretary-general for communications and public information in the UN is said to be eloquent and excellent at public diplomacy.
PRESIDENT VAIRA VIKE-FREIBERGA - LATVIAPresident Vaira Vike-Freiberga has led Latvia since 1999. She has been working for over a year as Kofi Annan's special envoy for United Nations reforms. The popular Baltic leader is a strong supporter of the US policy in Iraq and is believed to enjoy the support of the White House and certain EU countries.