<P> The President's role as defender of the Constitution and the powers as Head of State, especially in relation to those exercised by the Prime Minister as leader of the government, have changed over time . In particular, Presidents have made a number of interventions into government and lawmaking, which have established and challenged some conventions concerning Presidential intervention . </P> <P> In 1979, the Prime Minister, Charan Singh, did not enjoy a Parliamentary majority . He responded to this by simply not advising the President to summon Parliament . Since then, Presidents have been more diligent in directing incoming Prime Ministers to convene Parliament and prove their majority within reasonable deadlines (2 to 3 weeks). In the interim period, the Prime Ministers are generally restrained from making policy decisions . </P> <P> Since the 1990s, Parliamentary elections have generally not resulted in a single party or group of parties having a distinct majority, until the 2014 Lok Sabha elections when BJP received a clear majority . In such cases, Presidents have used their discretion and directed Prime Ministerial aspirants to establish their credentials before being invited to form the government . Typically, the aspirants have been asked to produce letters from various party leaders, with the signatures of all the MPs who are pledging support to their candidature . This is in addition to the requirement that a Prime Minister prove he has the support of the Lok Sabha (by a vote on the floor of the House) within weeks of being sworn into office . </P> <P> Since the Indian Constitution does not provide any time limit within which the President is to declare his assent or refusal, the President could exercise a "pocket veto" by not taking any action for an indefinite time . The veto was used in 1986 by President Zail Singh over the Postal Bill . The President did not give assent to the bill, arguing that its scope was too sweeping and would give the government arbitrary powers to intercept postal communications indiscriminately . </P>

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