NEW DELHI — One of India’s feistiest opposition parties cruised to victory in state elections in West Bengal on Sunday, dealing a blow to Prime Minister Narendra Modi in a campaign held during a catastrophic surge in Covid-19 infections.
Top parties had campaigned relentlessly in West Bengal, one of India’s most populous states and a stronghold of opposition to Mr. Modi, India’s most powerful prime minister in decades. Even with cases soaring and more and more people dying across India, Mr. Modi and other politicians held enormous rallies up and down the state, which critics said helped spread the virus.
By Sunday night, with nearly all the votes counted, Mr. Modi’s Bharatiya Janata Party was badly trailing despite its heavy investment in West Bengal, a prize it desperately wanted to win. The party won more seats in the state assembly than it took in the last election — a sign of how dominant it has become nationwide. Nevertheless, the All India Trinamool Congress party, which holds power in the state, was safely ahead.
That party is led by Mamata Banerjee, India’s only female chief minister, who has developed her own cult of personality and a reputation as a street fighter strong enough to ward off the most withering attacks from the B.J.P., as Mr. Modi’s Hindu nationalist party is commonly known.
Mr. Modi sent out a Twitter message on Sunday night that said, “Congratulations to Mamata Didi,” which means sister Mamata.
“The Centre will continue to extend all possible support to the West Bengal Government to fulfill people’s aspirations and also to overcome the COVID-19 pandemic,” Mr. Modi wrote.
Three other states and a federal territory also released election results on Sunday, and they contained few surprises.
Kerala, in the south, will remain under the control of the Left Democratic Front, an alliance of centrist and left-leaning parties.
Tamil Nadu, also in the south and home to some of India’s most innovative technology companies, will be controlled by the Dravida Munnetra Kazhagam, a centrist alliance, as exit polls had predicted.
Assam, a northeastern region racked by some divisive religious and citizenship issues, remained a stronghold of the B.J.P.
And a regional party aligned with the B.J.P. won the most assembly seats in Puducherry, a former French colony on India’s east coast that is now a territory controlled by the central government.
“The West Bengal results tell us that Modi’s personal, divisive and aggressive campaign in West Bengal backfired,” said Gilles Verniers, a professor of political science at Ashoka University near New Delhi.
Many Indians were stunned that these elections were even held. The country is facing its greatest crisis in recent memory, with a second wave of the coronavirus causing vast sickness and death. Hospitals are so full that people are dying in the streets.
Cremation grounds are working day and night, burning thousands of bodies. In New Delhi, there is an acute shortage of medical oxygen, and dozens have died gasping for breath in their hospital beds.
On Sunday, India reported around 400,000 new infections and nearly 3,700 deaths, its highest daily toll yet. Experts say that is a vast undercount and that the real toll is far higher.
Mr. Modi met on Sunday with senior officials to discuss the oxygen shortage, and the Indian news media reported that his government was also increasingly concerned that doctors and nurses had become overwhelmed and exhausted. Some media outlets reported that the Modi administration was considering drafting medical school students in their final year to help.
Critics have assailed Mr. Modi’s handling of the crisis. His government failed to heed warnings from scientists, and its own Covid-19 task force did not meet for months. To signal that India was open for business, Mr. Modi himself declared a premature victory over Covid in late January, during what proved to be a mere lull in infections.
Much of India has since dropped its guard. That, along with the emergence of more dangerous variants and a sluggish vaccine campaign, is believed to have fueled the staggering number of infections, the worst numbers the world has seen.
The West Bengal election was held in stages, beginning in late March and running through last week. Many critics said it should have been called off, or that rallies, at the very least, should have been banned.
But that did not happen. Mr. Modi’s party went on the attack, telling Hindu voters that if they didn’t vote for Mr. Modi’s party, their most deeply held religious beliefs might be in danger.
Ms. Banerjee, 66, who has led the state for a decade, dismissed that as nonsense. Long popular among Muslims and other minorities, she also appealed directly to Hindus, painting the B.J.P. as troublemaking outsiders.
With almost all votes counted, it appeared she may have lost her own assembly seat in a tight race, but that will not stop her from becoming chief minister, the top state-level executive in India’s decentralized system. Under India’s Constitution, the chief minister can be appointed for up to six months and within that period must become a member of the state Parliament. With Ms. Banerjee’s party firmly in control, that will not be a difficult task for her.
Mr. Modi traveled to West Bengal about a dozen times for packed rallies (often failing to wear a mask, along with many people in the crowds). His face was so ubiquitous that people joked that he seemed to be running for chief minister.
Ms. Banerjee’s campaign slogan was simple and nativist: “Bengal chooses its own daughter.”
Even with this loss, Mr. Modi’s party is by far the dominant political outfit in India, and there is no other political figure who comes close to his popularity.
Still, given how hard he fought to win West Bengal, some analysts saw Sunday’s results as a blow to him, with Ms. Banerjee and other regional figures — specifically, M.K. Stalin in Tamil Nadu and Pinarayi Vijayan in Kerala — gaining strength.
“This government is now battling a public backlash on their mishandling of the Covid pandemic,” said Arati Jerath, a well-known political commentator. “I think it is bad news for Modi that three powerful regional chieftains are emerging from these elections.”