Amanah central committee member Datuk Wan Abdul Rahim Wan Abdullah confirmed that Husam recently tendered his resignation letter.
"But he is still a party member and the Kota Baru division chief," he said when contacted on Monday (Sept 14).
Wan Abdul Rahim added that it was important to carry out in-depth research, which Husam had initiated, to gauge Amanah's chances of winning in the PAS-controlled state.
"Husam felt the need to relinquish his central party post so that he could focus his attention entirely on Kelantan.
"We may have lost the battle there in the last general election, but we still have a fighting chance in the next general election.
"We need the right strategy to win," he said.
In the last general election, Amanah, which contested under the PKR banner, failed to secure any seats in Kelantan.