If the position of the President of the National Authority becomes vacant in the absence of the Legislative Council, the President of the Palestinian National Council shall assume the duties of the Presidency of the National Authority temporarily, for a period not exceeding ninety days, during which free and direct elections shall be held to elect a new President in accordance with the Palestinian Elections Law. If they cannot be held during that period due to force majeure, they shall be extended by a decision of the Palestinian Central Council for another period, and for one time only.

Abu Mazen's announcement has nothing to do with his health condition. There are American pressures that pushed him to make this announcement.