Otunnu, 75, is the oldest candidate in the race to lead the world body when Guterres’ second five-year term ends on December 31. 

The veteran diplomat previously served as Uganda’s foreign minister for a brief period and as the country’s ambassador to the United Nations. 

He also served as a UN under-secretary-general and special representative for children and armed conflict.

Otunnu, who previously ran as an opposition presidential candidate in Uganda, joins contenders from Chile, Ecuador, Argentina, Costa Rica, Guyana and Senegal.

Senegal’s former president Macky Sall is among the candidates seeking the top UN post. Four of the six other candidates took part in a televised debate on Thursday.

The selection process is expected to begin later this month, when the 15-member UN Security Council holds its first closed-door, anonymous vote — known as a “straw poll” — to evaluate support for the candidates.

Further rounds of voting will follow until one candidate secures at least nine votes and avoids a veto from any of the council’s five permanent members: the United States, Britain, China, France and Russia.

The Security Council will then recommend its preferred candidate to the UN General Assembly, which will formally appoint the next secretary-general.

The new UN chief will assume office on January 1, 2027.