Much is at stake in a campaign that began with the ruling party of Prime Minister Atal Behari Vajpayee, buoyed by a booming economy, confident of victory but now finding the main opposition Congress party doing better than expected.
Monday's last round of the three-week poll, the world's largest democratic exercise, is the toughest for Vajpayee's Bharatiya Janata Party (BJP), which leads the ruling coalition.
Opinion polls predict the BJP and its allies will struggle to win more than a third of the seats being contested on Monday and could leave his coalition short of a majority.
The campaign, which ended on Saturday has become nastier as the race has narrowed, leaving investors nervous about the poll's outcome.
"Today, the BJP is anxious. Their coalition is unravelling and they are looking for new partners," head of the main opposition party Sonia Gandhi, told thousands of flag-waving supporters in sweltering heat in the capital on Saturday.
Gandhi, in her final rally for the campaign, accused the BJP of targeting religious minorities, rampant corruption during its five-year rule and throwing thousands out of work by privatising state companies.
PM Atal Behari Vajpayee was
confident of victory
Leading BJP campaigner Narendra Modi has used every opportunity to attack the foreign origin of Gandhi, the Italian-born widow of assassinated former Prime Minister Rajiv Gandhi.
Speaking at a rally in the southern state of Tamil Nadu, where Rajiv Gandhi was assassinated, Gandhi responded by saying she was ready to suffer the same fate as her husband and her mother-in-law Indira Gandhi, who was also assassinated.
"As I stand on this soil with which the blood of my husband has mingled, I say I will not hesitate to share this honour," she said.
The latest by NDTV and the Indian Express newspaper predicted the BJP and its allies would pick up just 67 of the 182 seats at stake in the final round of voting in 16 states on
That would leave them with between 240 and 260 seats overall in the 545-member lower house of parliament, short of a majority, the poll said, and well down on the number of seats in the last parliament.
Sonia Gandhi is being attacked
for her Italian origins
Vajpayee called the election six months early to capitalise on a strong economy, a good monsoon and improving ties with old foe Pakistan.
But his party's campaign motto, "India shining", appears to have backfired among the country's impoverished rural masses, who feel excluded from an economic resurgence that has mainly benefited the urban middle class.
Gandhi said "India Shining" meant nothing more than higher prices for the poor and was benefiting a select few.
The BJP has now shifted tack, concentrating instead on promoting itself as the only party capable of forming a coalition in the fractious world of Indian politics.