An amendment of the Constitution can be initiated only by the introduction of a Bill in either house of Parliament. The Bill must pass in both the houses separately by absolute (more that 50% of strength) and special majority (two-thirds of present and voting).
If there is a disagreement between the two houses on a constitution amendment bill, there is no provision of joint sitting to resolve the deadlock. Once the bill is passed in both houses, the bill is sent to president for approval. The 24th Amendment Act of 1971 had made it obligatory for the President to give his assent to a constitutional Amendment Bill. Thus, for a Constitution amendment bill, a President can neither withhold his assent not return the bill for reconsideration.