Results in the general election put opposition leader Narendra Modi on course for a landslide victory on Friday, handing him an unfettered mandate to launch his agenda to revive growth and create jobs.
Modi has promised to unblock stalled investments in power, road and rail projects to revive economic growth that has fallen to a decade low of below 5 percent.
Count of voting at local time 1056 (0526 GMT):
BJP-led alliance ahead in 324 seats, BJP in 272 seats
Congress-led alliance leading in 66 seats, Congress in 50 seats
Seats needed for majority - 272
BJP on course for strongest showing by a political party since 1984. Congress party headed towards its worst seat tally in India's election history.
Rajnath Singh, president of the BJP, congratulated Modi on the party's performance in the elections, he tweeted.
BJP ahead in 62 of 80 seats in Uttar Pradesh. In New Delhi, the party is headed for a clean sweep, leading in all seven seats.
"My blessings are there. The country will develop. My blessings are there," said 95-year-old Hiraben, Modi's mother.
In Modi home state of Gujarat, BJP on course to win all 26 parliamentary seats.
Indian shares rally to record highs, rupee strengthens to near a 10-month high against the U.S. dollar. The Sensex is up almost 1,000 points, or almost 4 percent, at 1045 (0516 GMT).
"(BJP) are getting a clear mandate, so they need to be quick in fulfilling their promises to revive growth. The sentiment in corporate India is hugely positive," said Sunil Duggal, chief executive officer at Dabur India DABU.NS.
Arun Jaitley, widely seen as India's next finance minister if the BJP-led alliance wins, trailing in Amritsar.
Congress party leader Rahul Gandhi, scion of the Nehru-Gandhi dynasty, holds a slender lead in his Amethi constituency in Uttar Pradesh. Television star-turned-BJP politician Smriti Irani trails.
Jayalalithaa Jayaram's AIADMK party is leading in 35 of 39 parliamentary seats in state of Tamil Nadu.
"It looks pretty bleak at the moment," Congress leader Abhishek Manu Singhvi said.
In West Bengal, Mamata Banerjee-led Trinamool Congress party is leading in 33 of 42 seats.
Ex-Infosys executives Nandan Nilekani, representing Congress, and V. Balakrishnan, of the Aam Aadmi Party, trailing in Bangalore constituencies.
BJP's prime-ministerial candidate Narendra Modi is leading in both of his seats, in the holy city of Varanasi in Uttar Pradesh state, and in Vadodara in Gujarat.
Congress party president Sonia Gandhi leading in her Rae Bareli constituency.
Aam Aadmi Party, or "Common Man's Party", leading in four seats.
Industrialist Naveen Jindal trails in his bid to be re-elected from Kurukshetra constituency in northern Haryana state.
Senior Congress leader Ajay Maken admits to errors in the campaign. "I think that we were not able to convey to the people the amount of work we have done ... that needed to be communicated more to the people," he said.
Source for results: Election Commission website, TV news channels.