These are designed to undermine the other while highlighting their own achievements and no attack goes unanswered.
So it was on Monday when Mr Modi said, during a video conference with NRIs in 18 Indian cities that he had scripted Gujarat's growth story in a land of sand and no river, and managed high agricultural yield amid a drought. Mr Modi is wont to comparing his state's performance favourably to that of states like Bihar which have an abundance of natural resources.
Bihar chief minister Nitish Kumar had been listening. At a press conference after his weekly meet-the-people, Mr Kumar pointed out that landlocked states like Bihar had their problems and states with coasts, read Mr Modi's Gujarat, had unique advantages like the ports that are a centre of trade.
Mr Kumar and Mr Modi share a mutual antipathy that has repeatedly threatened to derail the longstanding partnership of their parties, the Janata Dal (United) and the BJP. Especially now, with Mr Modi being seen as a frontrunner to be named the prime ministerial candidate of the NDA, the national alliance that the two parties are part of, for the general elections 2014.
Mr Kumar has made it clear to the BJP that picking Mr Modi to lead will mean a parting of ways with the JD(U). For now both partners are attempting to de-escalate hostilities, though the Nitish-Modi feud clearly has its own dynamics.