Mohun Bagan general secretary Srinjoy Bose on Tuesday quit from his position "citing personal reasons".
The development coincided with the expiry of the present committee of the Mohun Bagan.
Bose could have run the show till a new executive is formed after the elections but he opted to step down.
"For personal reasons, I express my heartfelt desire to be relieved of my responsibilities as general secretary of the club and tender my resignation with immediate effect," Bose said in his letter to the president and members of the executive committee.
"In all fairness, my duties stand fulfilled. I'm confident that the club shall continue to be managed with best competence as it has been done over the years," he said, with his "heartfelt gratitude" to the West Bengal chief minister Mamata Banerjee.
The decision is also seen as a calculated move by Bose in the build-up to the club's elections.
Mohun Bagan has been the team to beat in the ISL after Sanjiv Goenka-owned ATK acquired a majority stake in the club before the last season's ISL to make it ATK Mohun Bagan.
However, few supporters of the club are reportedly unhappy with the century-old club's name being prefixed by its investors ATK.
On form, the newly-formed entity, ATK Mohun Bagan, finished runner-up behind Mumbai City FC in the last season.
This time, ATK Mohun Bagan has made it two wins in a row after thrashing arch-rival East Bengal 3-0 in the season's first derby to lead the group standings with six points.