The United Nations' 193-member states are expected to appoint Portugal's former Prime Minister Antonio Guterres as the world body's next secretary-general.
Peter Thompson, president of the General Assembly, said in a statement that he hoped Guterres would be approved by a unanimous vote on Thursday.
Guterres, 67, was nominated by acclamation in the 15-member Security Council last week to replace Ban Ki-moon whose second five-year term ends on December 31. He would be the ninth secretary-general in the organisation's 71-year history.
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Aside from leading Portugal from 1995 to 2002, Guterres spent 10 years as the United Nations' high commissioner on refugees from 2005 to 2015.
Guterres' nomination disappointed those who had campaigned for a woman to lead the world body for the first time and also those who hoped the next secretary-general would come from an Eastern European country, but diplomats stressed they were voting for the best candidate regardless of other criteria.
"He'll take over on the first of January at a crucial time for the UN, when it is facing huge challenges on peace and security but also on international development and human rights. And the world needs a strong United Nations and he is the best possible leader to build on the work of his predecessors to provide that leadership," Britain's UN Ambassador Matthew Rycroft said.
The secretary-general manages a staff of 44,000 in addition to more than 100,000 peacekeepers. The position's responsibilities include dealing with issues such as human rights, refugees and climate change as well as fund raising for the world body's various campaigns.
