The Bharatiya Janata Party (BJP) has picked up more popular support and remains best placed to lead a coalition government after a national election due by May, an opinion poll showed on Thursday.
The ruling Congress will slump to its weakest showing in parliament since independence in 1947, the Times Now-CVoter poll forecast, presenting a challenge to Rahul Gandhi, who is leading the party in its toughest election battle yet.
More than 700 million people are eligible to vote in the world's largest democratic exercise to choose a new government. India, Asia's third largest economy, is growing at its slowest pace in a decade, choking off employment opportunities for tens of hundreds of youth who join the workforce each month.
The BJP and its allies led by Narendra Modi will win 227 seats of the 543 at stake in the Lok Sabha, the poll said.
To rule a party requires the support of 272 lawmakers, and the BJP will have to cast around for support among regional groups who are also expected to do well in the election.
A survey conducted in October by the same polling agency soon after the aggressive Modi was named the party's prime ministerial candidate put his party's support at 186 seats.
The latest poll was conducted in a sample of just over 14,000 voters across 28 states between January 15 to February 8. Local opinion polls have had a mixed record in the past, given the country's huge and diverse electorate.
Modi, a three-time chief minister of booming Gujarat, has steadily pulled ahead, promising to revive the economy, cut red tape and fight corruption.
On Thursday he received U.S. ambassador Nancy Powell at his home in the state capital Gandhinagar, the highest-level meeting since the U.S. State Department revoked his visa in 2005 over religious violence in Gujarat.
Rights groups and political rivals accuse Modi of failing to protect minority Muslims in the violence that gripped the state after a train carrying Hindu pilgrims was set on fire. Modi has denied any wrongdoing and a Supreme Court panel absolved him of any responsibility.
The Congress may end up with just 89 seats out of the 543 seats, the poll said, losing ground to the BJP in the big heartland states of northern but also southern India where its move to carve up another province has led to a revolt in the party.
Gandhi, the fourth generation member of the long-ruling Nehru-Gandhi dynasty, has struggled to draw support for the ruling party mired by corruption scandals and paralysis. He has himself seemed distant at times, unsure of how to stop the slide in the 129-year-old party's fortunes.
An anti-graft party that took Delhi by storm, winning power in a local election in December, will win seven seats in the national election, the survey said, far less than what its supporters are aiming for.
Since taking power in Delhi, the Aam Aadmi Party (AAP) has faced criticism for pursuing street activism even after coming into government and of making promises it is struggling to keep.