"The central committee meeting on 20 January will find a final solution to the political problem caused by the Prime Minister's illness," said Costas Skandelidis, the general secretary of the Panhellenic Socialist Movement (Pasok) central committee.
The committee would decide when Pasok's socialist parliamentary group should meet, Mr Skandelidis added, clearly referring to the group's responsibility to elect a successor to Mr Papandreou, 76.
Mr Skandelidis made his statements after a special meeting of the executive bureau ofPasok to consider the succession problem.
Greece has been without a functioning prime minister since 20 November when Mr Papandreou was taken into hospital with pneumonia. Since then he has been kept alive on life-support systems.
Doctors were examining the possibility yesterday of flying Mr Papandreou to the United States for further treatment. A state department official said that although an airlift request had not yet been made, American medical specialists were being sent to examine Mr Papandreou.
Now in his seventh week in critical condition in hospital, the Prime Minister has suffered heavy damage to his kidneys, the latest medical bulletin said.