India, Jan. 5 -- Bihar cabinet minister Nitin Nabin, who was appointed as the working president of the Bharatiya Janata Party (BJP) on December 14, is likely to be elevated as the president of the party next month. If that happens, he will become the 12th person to hold that post, but only the second person from the Kayastha sub-caste to do so. Is there a caste pattern to the post? How does it differ from the post in the Congress? Using their respective websites, HT has created a caste database of all national party presidents of the BJP and that of the Congress since 1947 to answer this question. This first of a two-part data series will first describe the social composition of national presidents. The second part will look at this compo...