By Sanjoy Majumder
BBC News, Delhi
Neither main party is expected to gain a clear majority
India has completed its last day of campaigning before the first phase of the month-long election starts in the world's largest democracy.
More than 700 million Indians overall are eligible to vote for seats in the lower house of parliament.
The incumbent Congress-led coalition government is facing a challenge from the main opposition BJP-led alliance.
It is also competing against a third front of communist and regional parties in a poll that is too close to call.
Voting takes place on Thursday in more than 100 parliamentary constituencies spread across the country, including volatile areas in north and central India.
More than two million security personnel are expected to be deployed, especially after a string of recent attacks by Maoist rebels who have threatened to disrupt the vote.
Ahead of the polls, both the leading candidates for prime minister, the incumbent Manmohan Singh and LK Advani of the Bharatiya Janata Party (BJP) addressed campaign rallies.
Neither party is expected to gain a clear majority and will have to depend on the support of smaller parties to form a government and the campaign rhetoric in recent days has become increasingly bitter.
While security and the economy are key election issues, especially after last year's attacks in Mumbai and the global economic meltdown, local and regional issues could well swing the vote.