With the elections widely expected to lead to a hung parliament, all eyes will be on President Pratibha Patil who will decide who to invite to form a government after the votes get counted May 16.
"The president will have a most crucial role in such a fluid situation," senior advocate and constitutional expert Anil Dewan said.
K K Venugopal, another leading constitutional expert and lawyer, said: "The safest and most prudent rule for the president will be to first invite either the single largest party, though a minority, or a pre-poll alliance with the largest number of MPs to form the government."
Image: President Pratibha Patil exercises her franchise at the Rashtrapati Bhawan polling booth in New Delhi on May 7, 2009. (Copyright PTI. Unauthorised reproduction is prohibited.)
Who will get to rule India?