The businessman, who ran as an independent candidate at the federal election in the seat of Nicholls and succeeded in making the seat marginal, said donations for his political campaign would impact his effectiveness on council.
“Under the new local government act, donations received for a federal campaign must be considered when assessing a conflict of interest with decisions before council,” Mr Priestly said.
Mr Priestly said the overwhelming support he received for his tilt at federal parliament included hundreds of financial donations and in kind support.
“It was only during my federal campaign that I came to understand the implications of the new local government act,” he said.
“An analysis of council agenda items found that I would have a conflict of interest on many matters that come before council, as people who supported my campaign are also leaders of community groups, sporting clubs, business owners etc, requiring me to absent myself from many decisions if I return to council.
“This issue was not widely understood when I sought advice about running for the federal election so, with a heavy heart, I must resign from council, effective immediately.”
Mr Priestly said the outcome was personally disappointing and for the many members of the community who supported his participation as a councillor.
“It is the lesser of two evils,” he said.
“If I stay on council I would need to absent my self from many decisions, and not be an effective councillor. I wish the new councillor appointed all the best, thank the community for supporting me, my fellow councillors and council staff for their support and work during my time on council.”
Given the next election is not until October 2024, a countback will be required to elect a replacement councillor.
All candidates from the original election are included in the countback and Mr Priestly would be eliminated after first preferences, with his second preference votes distributed.
The first unelected councillor from the original election to reach a quota would then be elected.
Former mayor Dinny Adem, who was 161 votes short of the quota needed at the last election, is the most likely although the countback process is complex.
Mr Adem confirmed he would serve if elected on countback.