Indian prime minister Narendra Modi’s party has won a resounding election victory in West Bengal, a state which had been a rare opposition stronghold, expanding his unrivalled consolidation of power across the country.

It is the first time that Modi’s Bharatiya Janata Party (BJP) have won assembly elections in West Bengal, a large and politically significant state in eastern India.

Over the past 15 years, the state had been ruled by Trinamool Congress (TMC), a key opposition party, under the leadership ofMamata Banerjee, their female chief minister. Banerjee had been one of the most outspoken critics of Modi and his religious nationalist agenda over his 12 years in power.

But in a result which is set to have significant implications for India’s political landscape and another demoralising blow to the already weakened opposition, the BJP looked set to win more than 205 out of 294 seats in Bengal’s state assembly, a landmark majority.

Modi said in a statement the West Bengal assembly elections “will be remembered forever. People’s power has prevailed and BJP’s politics of good governance has triumphed. I bow to each and every person of West Bengal.”

The victory in West Bengal, which had been a longstanding ambition for the BJP, furthers the Hindu nationalist party’s unfettered control over state and central governments in India, now expanding its influence over the eastern part of the country.

Since Modi became prime minister in 2014, the BJP’s dominance over politics, and the reach of their political agenda which seeks to remake India intoa Hindu rather than secular country, has continued to grow while the opposition has been fractured and divided by infighting.

On Monday, the BJP were also re-elected in the eastern state of Assam, giving the party power in 20 out of 28 states.

The result followed a highly controversial exercise by the BJP government to revise West Bengal’s electoral roll, under the guise of “purging” it of illegal voters. As a result of the project, called a special intensive revision (SIR), more than 2.7 million voters were removed from the vote register. Analysis showed that Muslims and other minorities – who traditionally do not support the BJP – were disproportionately targeted.

Many had not been allowed to challenge their expulsion in time for the polls. Critics and TMC leaders alleged the SIR exercise was an attempt by the BJP to skew the election in their favour, which was denied by the government.

Rahul Verma, a fellow at the Centre for Policy Research in Delhi, said the BJP’s win in West Bengal was the culmination of a “seven-year project” by the party leadership and cadre.

He cited anti-incumbency and a strong dissatisfaction with TMC, and their interference in daily life, as a critical factor which lost them votes. He said BJP had run a much smoother campaign than in previous years, when they had previously been criticised as “outsiders” who threatened the Bengali cultural and linguistic identity.

“The BJP had a strong and well organised presence in West Bengal and Modi is seen as a charismatic leader,” said Verma. “This kind of result also wouldn’t have happened without a consolidation of the Hindu vote.”

For Verma, the outcome signalled that while the SIR exercise was unlikely to have swung the whole vote for the BJP, it nonetheless played “a marginal but still important role in these results”.

Monday’s victories for the BJP in West Bengal, Assam and the small territory of Puducherry signal a return to the strong political momentum claimed by the party prior to the 2024 general election, when they lost their outright majority in parliament.

It also dealt a further blow to the Indian National Congress, the main opposition party, which faced further losses and saw two of their allied opposition parties removed from power.

“Looking back at 2024, it now seems like that was a temporary setback to BJP,” said Verma. “They are returned to their dominant position. With very successive defeat, there is much more pressure mounting on the opposition, while the BJP looks even more invincible.”

Nonetheless, analysts emphasised the BJP could still face a volatile future, as the economic impact of the Iran war and resulting energy crisis continues to mount, with issues of mass unemployment remaining unresolved.

Monday’s results also made it clear that southern India remains one opposition stronghold that the BJP has yet to successfully penetrate. In Kerala, which has a long history of electing leftist and communist governments, the Congress party defeated the Communist-led alliance for the first time in a decade, while the BJP made small gains.

In a big electoral shock in Tamil Nadu, political newcomer and former film star C Joseph Vijay and his Tamilaga Vettri Kazhagam party became the first new political outfit to gain power in the state for almost 50 years.