Diplomatic sources on Wednesday said the resolution to extend the mandate of the mission, which was to expire on Friday, will be co-sponsored by all 15 Security Council members.
The council's current president, Russian Ambassador Andrei Denissov, said the vote will proceed on Thursday.
The resolution needs a minimum of nine votes to pass. Any of the five permanent council members, the United States, Russia, UK, France and China, could veto it.
The proposed resolution states the Security Council is "reaffirming that the United Nations should play a leading role in assisting the Iraqi people and government in the formation of institutions for representative government".
The Security Council is also "reaffirming the independence, sovereignty, unity and territorial integrity of Iraq".
Currently the UN mission in Iraq (UNAMI) is focused on providing aid and advice to Iraqi authorities that will hold the country's national conference on 14 August.
The conference is aimed at launching the political process ahead of general elections in January 2005.
The resolution comes amid continuing concerns over the safety and security of UN staff in Iraq.
The UN's humanitarian mission for Iraq is currently based in neighbouring Jordan.