Chief Electoral Officer (CEO)- As per section 13A of the Representation of the People Act 1950, read with section 20 of the Representation of the People Act, 1951, the Chief Electoral Officer of a State/ Union Territory is authorised to supervise the election work in the State/Union Territory subject to the overall superintendence, direction and control of the Election Commission. The District Election Officer (DEO) -As per section 13AA of the Representation of the People Act 1950, subject to the superintendence, direction and control of the Chief Electoral Officer, the District Election Officer supervises the election work of a district. Returning Officer (RO) -The Returning Officer of a parliamentary or assembly constituency is responsible for the conduct of elections in the parliamentary or assembly constituency concerned as per section 21 of the Representation of the People Act 1951. Electoral Registration Officer (ERO)-The Electoral Registration officer is responsible for the preparation of electoral rolls for a parliamentary / assembly constituency. Presiding Officer -The Presiding Officer with the assistance of polling officers conducts the poll at a polling station. Observer -Under section 20B of the Representationof the People Act 1951, the Election Commission of India nominates officers of Government as Observers (General Observers and Election Expenditure Observers) for parliamentary and assembly constituencies. They perform such functions as are entrusted to them by the Commission. Earlier, the appointment of Observers was made under the plenary powers of the Commission. But with the amendments made to the Representation of the People Act, 1951 in 1996, these are now statutory appointments. They report directly to the Commission.