I MET SREK AT A CAFE IN KOLKATA, on the last evening of May. Sipping cold coffee and wiping sweat off his forehead despite the air-conditioning, the 19-year-old undergraduate student, who heads a small band of graffiti artists calling themselves Zephyr, told me of how, earlier that month, soon after municipal polls concluded on 18 April, he had tried to “rid the City of Joy of its eyesore walls.” In the dead of night, he snuck out of his house, in north Kolkata, and hopped onto a friend’s motorbike. Half an hour later, the pair arrived at Jadavpur, an area in the city’s south. The two-person “cru”—jargon for crew—pulled out cans of spray paint, and prepared to “reclaim” with their art a wall covered in political graffiti.

“But before we could start painting, a group of people charged at us,” he said. “We hurriedly picked up our bag and took the escape route,” predefined on an earlier inspection. “We had a narrow escape. Had Shaf, the fellow member of our gang, not been aware of the geography of the area, only god knows what would have became of us.”

Their pursuers were cadres of the Trinamool Congress, or TMC, the ruling party of West Bengal. Since it assumed power in 2011, ending 34 years of rule by the Communist Party of India (Marxist), or CPI(M), it has forcefully asserted its claim to thousands of walls across the city, covering them with party slogans and symbology. Its graffiti gangs are particularly active before elections, as they were in the lead-up to the April polls, which the TMC won. So are their rivals from other parties, who challenge the incumbent party’s graffiti with their own. Many in the city see such graffiti as a blight, and some artists and residents are resisting political dominance over Kolkata’s walls. But the TMC is jealously holding on.