India's main stock market, the Sensex, leapt to a record high, jumping more than 5 per cent and passing 25,000 points as news of the BJP's performance hit the markets.
The fate of the rival Congress was summed up by the fact that Rahul Gandhi, who headed the ruling party's campaign, was fighting to hold on to his own seat in the Uttar Pradesh district of Amethi. His mother, Sonia Gandhi, seemed set to hang on to her seat in the neighbouring constituency of Rae Bareli, though perhaps with a reduced majority.
The party now faces the difficult challenge of sitting down and working out what went so badly wrong. There has even been speculation that the future of India's first family of politics could be over.
By contrast Modi, who contested from two seats, won by a margin of more than 300,000 people in one of them, Vadodara, and appeared to be comfortably ahead in the second, Varanasi.
Milan Vaishnav, an expert on Indian politics from the Carnegie Endowment in Washington, said Modi's message of development and jobs had struck a chord with hundreds of millions of Indians who were anxious about the state of the economy, corruption and a lack of opportunities.
It had helped the BJP that the Congress had failed to put up a clear leader, given that the party had declined to name Rahul Gandhi as its prime ministerial candidate.
"There was a pan-India sense of dissatisfaction with the economy. And Mr Modi's relentless campaign message about jobs and development proved to be so effective," he said.
Forecasters suggested Modi was on course to secure a clear majority and win the largest number of seats since 1984 when Rajiv Gandhi won a landslide on a wave of sympathy and anguish following the assassination of his mother, Indira Gandhi.
No party has won a simple majority since 1989 and the result would be a huge victory for Modi personally, and not just the BJP. The son of a tea salesman who later spent many years working for a Hindu nationalist organisation, Modi campaigned on a message of growth and development and tapped into the aspirations of hundreds of millions of people. He now has a huge mandate to enact his policies.
His professional, stage-managed campaign stood in stark contrast to the often lacklustre effort by the Congress and Rahul Gandhi who stressed to people that his Government was behind various welfare schemes they had access to.
How India will change under new leader
Economy
Narendra Modi campaigned on a platform of development and growth. He promised to offer a "red carpet" for investors and not more red tape. Large parts of the corporate world, both domestic and international, have supported his rise. Economist Vivek Dehejia said there were several things Modi could do quickly, such as change labour laws which businesses complain are restrictive. He could also offer a clearer taxation policy.
Cultural
There is a clear cultural element contained within Modi's Hindu nationalist party's plans. Under the last BJP government, school text books were changed to reflect a certain view of history and that is likely to happen again.
The manifesto also promises to build a temple in dedication to Hindu deity Lord Ram at a disputed site in Uttar Pradesh, that was once the location of a mosque. The mosque was pulled down in 1992 leading to widespread clashes between Hindus and Muslims. The BJP has also vowed to introduce a "Uniform Civil Code" that would end the use of traditional laws by religious communities. It also plans to scrap so-called Article 370 of the Constitution, which gives special status to Kashmir.
The RSS, a Hindu nationalist organisation of which Modi was once a member, is likely to have influence on the BJP Government.
Foreign policy
Most believe Modi feels much easier looking eastwards, to Asian nations such as Japan, Singapore and Indonesia, than he does towards the West. It may be one of these countries that Modi chooses for his first overseas visit as PM.
The United States famously refused him a visa in 2005, something that still hugely rankles with both him and his supporters, and while the US has since sought to engage with Modi, the visa issue remains unclear.
Milan Vaishnav of the Carnegie Endowment in Washington believes that in economic terms, India and the US could help each other and that bringing in investment would support Modi's campaign vow. Yet he said that India's strategic relationship with the US would be more problematic. He said he believed Modi will attend the United Nations General Assembly in New York in September.
Relationship with Pakistan
Modi and advisers have talked about getting tough with Pakistan and have criticised the way they claim Prime Minister Manmohan Singh failed to respond to repeated border provocations and the killing of Indian troops.
But another theory is that Modi, as a conservative, may have more chance of brokering a breakthrough with his counterpart in Pakistan, Nawaz Sharif. Analysts point out that in 1999, it was the BJP leader Atal Behari Vajpayee who reached out to Pakistan - then also led by Sharif - by taking a bus to Lahore and trying to strike a deal.
Communal relations
Modi has never escaped the accusations levelled at him over the 2002 killings of Muslims in Gujarat but his supporters point out there have been no communal clashes there since. During the campaign he stressed development and growth and said all communities would benefit from them. However, a number of his senior colleagues made communal comments and were accused of fomenting tension.
Many Muslims clearly distrust Modi, who has never apologised for what happened on his watch.
- Independent
