Indians were voting in the first stage of a staggered general election on Thursday just as the economy is hit by a slowdown and with polls showing the main national parties may struggle to form a stable coalition.
The ruling Congress party-led coalition appears to lead against an alliance headed by the Hindu-nationalist Bharatiya Janata Party (BJP), but both may need the support of a host of smaller regional parties to win office.
More than 140 million people can vote on Thursday in polls that cover some of India's poorest and most insurgency-ridden states.
The government has deployed more than two million security personnel across India as Maoist rebels have stepped up attacks on forces and threatened voters. New Delhi said it was also on heightened alert for militant infiltrations from Pakistan.
The outcome will be known on May 16 after five stages. India's elections are notoriously hard to predict and polls have been wrong in the past. Exit polls are banned for the election.
ARRAY OF CASTES
In Varanasi, the northern holy town known for its Hindu gurus, banners and bunting fluttered from rooftops. Many activists were seen moving around in cars and on motorbikes plastered with their party symbols and mugshots of their candidates.
An array of castes, religions and ethnicities make up the 714 million people eligible voters in what is the world's largest democratic exercise.
The centre-left Congress is wooing voters with populist measures such as food subsidies and farm loan waivers in a country were hundreds of millions live below the poverty line.
The BJP accuses its main rival of poor governance and being weak on security, after a string of militant attacks last year culminated in a rampage in Mumbai by Islamist gunmen that killed 166 people and hiked tensions with nuclear-armed Pakistan.
Playing on many investors' minds is the fear of an unstable government, as tens of millions of jobs have already been lost in the economic slowdown. Many of Congress' economic reforms were blocked in its five years in power by the communists, who had propped up the government.
There are also investor worries over the rise of a group of smaller parties, known as the "Third Front", who are often seen as opportunist and an unknown quantity in government.
Highlighting India's internal security woes, states such as Bihar, Chhattisgarh and Jharkhand will vote on Thursday in the face of stepped-up Maoist attacks on security forces. The rebels warned they will cut off the hands of those who dare vote.
Dozens of people have been killed in Maoist violence in the past week and at least 20 died in separate gunbattles between police and insurgents in eastern India on Wednesday.