Hawa, a Hindi word for wind or air, carries a subtler meaning in Indian politics. A politician’s hawa is the tailwind that propels him to victory; it is the superior momentum that comes with being on a roll.

For the past five years in the world’s biggest democracy, one man, one party, and one ideological current have pretty much cornered all the hawa. A puffing guardian spirit tangibly energizes Narendra Modi, India’s prime minister; despite his modest stature, the bearded sixty-seven-year-old can fill a room with a swirling air of quiet purpose or, some would say, menace. All across the country hawa can be felt ruffling the ubiquitous orange flags of his Bharatiya Janata, or Indian People’s Party (BJP), and stirring the long-suppressed ambitions of the Sangh Parivar, the “family” of Hindu nationalist groups that is the party’s ideological home.

Modi, his party, and the Sangh have made remarkable gains since he assumed the BJP leadership in 2013. Before his rise, the party in various avatars had at times won power in some of India’s thirty-six states and territories. It had even led coalition governments in the capital, Delhi. Ideologically the BJP had long been the strongest challenger to the Indian National Congress, the legacy party of Mahatma Gandhi and Jawaharlal Nehru’s freedom struggle: since before independence in 1947, the Sangh’s dream of a muscular Hindu rashtra, or nation, has stood in contrast to the Congress’s vision of a secular India that gains strength from diversity.

Yet before Modi was plucked from his post as chief minister of the state of Gujarat (roughly equivalent to an American governor) and made the party’s candidate for prime minister, the BJP had seldom excelled outside the “cow belt,” a socially conservative and largely Hindi-speaking northwestern wedge of the Indian diamond. Other Indians, whether minority Muslims, Christians, Sikhs, or just differently observant Hindus, generally shunned the Sangh “family”: they were earnest and devoted, yes, but also frightening; it was an extreme Hindu nationalist, after all, who shot Gandhi in 1948. The BJP could raise an occasional clamor, but the actual agenda of Hindutva, or Hindu nationalism—demands such as banning beef, ending the alleged “appeasement” of minorities by politicians seeking their votes, building a temple to the god Ram on the ruins of a mosque at his supposed birthplace, being extra-tough on Pakistan, or replacing “Western” modes of thinking and behaving with ostensibly “authentic” Indian ones like Ayurvedic medicine or rather vague notions of “Indian” economics—gained only slow and uneven traction in practice.

Modi has changed all that. In 2014 he led the BJP to one of the most dramatic electoral upsets in India’s seventy years as a democracy. The party not only captured 282 of the 543 seats in the Lok Sabha, or lower house…