The Union executive consists of the President, the Vice-President, and the Council of Ministers with the Prime Minister as the head to aid and advise the President.
The President is elected by members of an electoral college consisting of elected members of both Houses of Parliament and Legislative Assemblies of the states in accordance with the system of proportional representation, by means of single transferable vote. To secure uniformity among state inter se, as well as parity between the states as a whole, and the Union, suitable weightage is given to each vote. The President must be a citizen of India, not less than 35 years of age, and qualified for election as member of the Lok Sabha. His term of office is five years, and he is eligible for re-election. His removal from office is to be in accordance with procedure prescribed in Article 61 of the Constitution. He may, by writing under his hand addressed to the Vice-President, resign his office.
Executive power of the Union is vested in the President, and is exercised by him either directly or through officers subordinate to him in accordance with the Constitution. Supreme command of defence forces of the Union also vests in him. The President summons, prorogues, addresses, sends messages to Parliament and dissolves the Lok Sabha, promulgates Ordinances at any time, except when both Houses of Parliament are in session, makes recommendations for introducing financial and money bills and gives assent to bills, grants pardons, reprieves, respites or remission of punishment or suspends, and remits or commutes sentences in certain cases. When there is a failure of the constitutional machinery in a state, he can assume to himself all, or any of the functions of the government of that state. The President can proclaim emergency in the country if he is satisfied that a grave emergency exists, whereby security of India or any part of its territory is threatened, whether by war or external aggression or armed rebellion.
The Vice-President is elected by members of an electoral college consisting of members of both Houses of Parliament in accordance with the system of proportional representation by means of single transferable vote. He must be a citizen of India, not less than 35 years of age, and eligible for election as a member of the Rajya Sabha. His term of office is five years, and he is eligible for re-election. His removal from office is to be in accordance with procedure prescribed in Article 67 b.
The Vice-President is ex-officio Chairman of the Rajya Sabha and acts as President when the latter is unable to discharge his functions due to absence, illness or any other cause, or till the election of a new President (to be held within six months when a vacancy is caused by death, resignation or removal or otherwise of President). While so acting, he ceases to perform the function of the Chairman of the Rajya Sabha.
There is a Council of Ministers headed by the Prime Minister to aid and advise the President in exercise of his functions. The Prime Minister is appointed by the President, who also appoints other ministers on the advice of Prime Minister. The Council is collectively responsible to the Lok Sabha. It is the duty of the Prime Minister to communicate to the President all decisions of Council of Ministers relating to administration of affairs of the Union and proposals for legislation and information relating to them.
The Council of Ministers comprises Ministers who are members of Cabinet, Ministers of State (independent charge), Ministers of State and Deputy Ministers.
Source: India Book - A Reference Annual