Ankur Rana types furiously into his phone, sending messages across the hundreds of WhatsApp groups he manages. "I have 400-450 WhatsApp groups which each have about 200-300 members. Apart from this, I have about 5,000 direct contacts. In this way, I personally reach 10-15,000 people every day," the social media coordinator for the Bharatiya Janata Party (BJP) in the Meerut parliamentary constituency in western Uttar Pradesh explained in the run-up to voting last month.