Sonia Gandhi’s decision to appoint five-term Berhampore MP Adhir Ranjan Chowdhury as the leader of the Congress in the Lok Sabha after Rahul Gandhi refused to take on the responsibility surprised many. With the party suffering from a continuing bout of poll debacle stress disorder, the Congress strongman from Bengal’s Murshidabad has a much larger and unenviable national role to play—put Narendra Modi’s government in the dock on crucial issues in Parliament. He spoke to Puneet Nicholas Yadav on the challenges ahead. Edited excerpts: