The President of Pakistan is indirectly elected by the Electoral College of Pakistan - a joint sitting of the Senate, National Assembly and Provincial Assemblies. Each elector casts a different number of votes. The general principle is that the total number of votes cast by members of Parliament equals the total number of votes cast by provincial legislators. Also, legislators from larger states cast more votes than those from smaller provinces. The actual calculation for votes cast by a particular state is calculated by dividing the state's population by the number of seats, which is again divided by the number of legislators from the state voting in the Electoral College. The constitution further states that election to the office of President must be held no earlier than sixty days and no later than thirty days before the expiration of the term of the incumbent president