One afternoon in April, Sugata Bose, a history professor at Harvard University, set out from his house in Sarat Bose Road to a lower-middle-class neighborhood in Jadavpur, the constituency in the eastern city of Kolkata where he is running for Parliament as a candidate of the Trinamool Congress, the governing party in the state of West Bengal.

Traveling in a Toyota minivan with some of his aides, Mr. Bose, 57, was besieged by party workers as soon as he reached the neighborhood, also called Jadavpur, where he was to campaign. Here, Mr. Bose climbed onto the back of a green jeep and disappeared into a labyrinth of narrow lanes, accompanied with loudspeakers and dozens of workers of the Trinamool Congress. Bicycles fitted with balloons of saffron, white and green — approximating the three-colored flower that is the symbol of the Trinamool Congress — followed Mr. Bose’s convoy.

For Mr. Bose, who is usually to be found in the cafes and classrooms of Cambridge, Mass., at this time of the year, it was an unexpected and novel way to spend the Indian summer season...