New Delhi, India: Amit Shah, president of India's ruling party, spent much of his son's wedding day this week on the phone to worried colleagues in the capital, where a disastrous election result is prompting those in power to rethink their policies and priorities.

According to two people at the event in the western city of Ahmedabad, Shah, who had overseen the New Delhi campaign for the Bharatiya Janata Party (BJP), cut a subdued figure. No firecrackers went off and the marching band did not play.

Tuesday's results showed Prime Minister Narendra Modi's BJP won just three of 70 seats. The remaining 67 went to the Aam Aadmi Party (AAP), a grass-roots anti-corruption movement led by 46-year-old former tax inspector, Arvind Kejriwal.

It was a crushing reversal for a party that swept to power in a national ballot last May, and a warning ahead of more significant state elections in the coming years that could directly impact Modi's ability to push through planned reforms.

‘Modi takes every election result seriously,’ said a BJP leader involved in the Delhi campaign, who asked not to be named. ‘You can't fool him, or tell him all is well and this election is not important.’

Modi's team blames the defeat on tactical errors, including the choice of a top former policewoman as lead campaigner and comments by hardline Hindu BJP lawmakers that alienated liberal Hindus, who put development and governance before religion.

‘The risk is not alienating the Muslims; they don't vote for us anyway,’ the BJP leader said. ‘The problem is, we alienate the moderate Hindus.’

While there were problems specific to Delhi, and Kejriwal's AAP has little traction elsewhere, his victory is likely to embolden other regional leaders, particularly after the main opposition Congress party failed to win a single seat.

The drubbing could also damage Modi's image among the broader public.

While Modi travelled to a Delhi campaign rally by helicopter to avoid the capital's gridlocked streets, Kejriwal went from door-to-door to spread his message, visited the city's slums and apologised for past mistakes - a rarity in Indian politics.

‘Kejriwal was able to effectively present himself as someone who is going to fight for the simple, common man," said N. Bhaskara Rao, chairman of the Centre for Media Studies in New Delhi. "The lesson for Modi is that he can't be complacent or aloof. He has to fight for every single vote.’

Next up Bihar

Modi needs to win most of the state elections in the next four years to gain control of both houses of parliament.

While the BJP and its allies have a majority in the lower house, they only have about a quarter of the 245 members in the upper house, where seats are distributed based on the strength of parties in state assemblies.

That has allowed the opposition parties to block some of his efforts to overhaul the economy and forced Modi to use decrees to push through decisions, a method even his supporters concede is unsustainable in the long term.

States that control about half of the seats in the upper house will go to the polls in the next three years, but the BJP does not have a strong foothold in many of them.

The next vote will be in Bihar, India's third-most-populous state, a territory that the BJP have never ruled outright. Elections in Bihar traditionally been driven by caste loyalties favouring regional parties.