Why was Nitin Nabin named BJP's Working President & not President?

Nitin Nabin is only the second person to hold the post of BJP's 'Working President' after the incumbent party president JP Nadda. The process to elect the new party chief may begin soon after January 14. This might be because 'Khar Maas', a month-long period considered inauspicious by Hindus, starts on December 16, NDTV reported. Nabin will be assisting Nadda.