Followers of Delhi's governing Aam Aadmi Party (Common Man's Party or AAP) danced in the streets yesterday after inflicting a crushing defeat on Prime Minister Narendra Modi's right-wing party in a key election in the capital.

The poll was the first electoral test for Modi's Bharatiya Janata Party after it passed a controversial nationality law which opponents say is anti-Muslim.

With counting of votes nearing completion, the AAP won 52 seats and was leading in another 10 of the 70 constituencies, while BJP won 7 seats and was leading in another one, the Election Commission said yesterday.

In the last elections held in 2015, the incumbent AAP won 67 out of 70 seats.

The Congress party, led by Italian-born Sonia Gandhi, repeated its 2015 performance and once again drew a blank. Full results were expected later yesterday.

"Dilliwalon [residents of Delhi], I love you," said AAP leader Arvind Kejriwal addressing party workers in New Delhi. He called the verdict a "win for Bharat Mata (Mother India)".

Modi, whose party swept to power in national elections last year, congratulated Kejriwal, the incumbent Delhi chief minister.

"Wishing them the very best in fulfilling the aspirations of the people of Delhi," Modi tweeted.

The BJP had launched an aggressive campaign to win the city of nearly 20 million people from the AAP, using the election to rally support for the law easing citizenship rules for religious minorities from Bangladesh, Pakistan and Afghanistan, but excluding Muslims.

At least 25 people have been killed in protests over the legislation so far.

The defeat in Delhi is the latest in a string of setbacks for the BJP at regional elections over the past two years.

The results show the BJP's divisive campaigning did not seem to pay off, as voters opted for incumbent Chief Minister Arvind Kejriwal's pro-poor policies, say experts.

"The Delhi result is extremely important because it signals a defeat of the politics of polarisation and division that BJP unleashed here," political analyst Zoya Hasan told Al Jazeera.

"This election was perhaps the most hate-filled election in India's electoral history. The Delhi voter has given a very good message to the country that hate politics doesn't work ..." said Hasan, who is also Professor Emeritus at Jawaharlal Nehru University (JNU).

"I hope the BJP will learn a lesson and shouldn't repeat this kind of blatant hate politics in other states that are going to elections in the next two years."

Nearly 61 percent of the capital's 14.7 million voters cast their ballots on Saturday in elections believed to be a litmus test for Modi in the wake of deadly anti-government protests that erupted nearly two months ago.

Neha Tyagi, vice president of AAP's women wing, said: "We were expecting a win, but the way it is trending we are happy."

"People have voted for the development work that AAP has been able to deliver in the last tenure," she told Al Jazeera.

The AAP's pro-poor policies have focused on fixing state-run schools and providing free healthcare and bus fares for women during its first term.

The BJP was accused of running a campaign based on religious polarisation, with many of its leaders targeting the Muslim community, who form a little more than 10 percent of the capital's population.

The New Delhi election is being seen as a test of Modi's popularity following months of deadly nationwide anti-government protests against a new Citizenship Amendment Act (CAA) that saw thousands of people take to the streets daily in the capital and across India.

The law makes it easier for non-Muslim immigrants from three neighbouring countries who came to India before 2015 to become Indian citizens, a provision that forces critics to call the legislation anti-Muslim.

The CAA and a proposed nationwide National Register of Citizens have stoked suspicion that Modi wants to turn secular India into a Hindu nation, something his party denies.

"People of Delhi have rejected BJP's politics of hate and divide," Gurucharan Singh, an AAP supporter, told Al Jazeera.

"BJP tried its best to make CAA a big election issue, but people gave its mandate to AAP on the development work it has done in the last five years and rejected BJP."

The Hindu-nationalist BJP led by Modi won a bigger majority in a general election in May, but it has lost a string of state elections since then. The party ran a campaign accusing protesters of supporting India's archrival Pakistan.