Durga Prasad, an 80-year-old farmer, was resting under the shade of a tree in front of his home when the party workers came. An app on their smartphones could tell them in an instant who Mr. Prasad was, whom he might vote for — and why he should be grateful to India’s prime minister, Narendra Modi. “You get installments of 2,000 rupees, right?” asked a local official from Mr. Modi’s Bharatiya Janata Party, or B.J.P. Mr. Prasad concurred. He receives $72 a year through a farmers’ welfare program started and branded by Mr. Modi.

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Persons: Durga Prasad, Prasad, Narendra Modi, “, ”, Modi’s, Modi Organizations: Modi’s Bharatiya Janata Party, Mr