"I have quit to facilitate the appointment of new President," Eshwarappa said, adding, he has sent his resignation letter to party president Rajnath Singh.
BJP sources said Eshwarappa, a prominent leader of the influential Kuruba community, had told the BJP leadership he was finding it difficult to manage the dual responsibilities of being a minister and party chief. Assembly polls are due in May.
65-year-old Eshwarappa had quit the erstwhile B S Yeddyurappa ministry in 2010 to take up the party post but returned to the Jagadish Shettar cabinet as Deputy Chief Minister and continued to head the party too.