Labour Party director on Friday. The ward to the north of Bolton town centre covers parts of areas such as Halliwell, Astley Bridge, and Tonge Moor.
Manchester Evening News reached out to all three of the councillors, but they did not wish to comment further on their reasons for leaving.
Labour leader Nick Peel, who took control of the group last month, said that while he was "disappointed", he still "remains focused" on rebuilding the public's trust in the group.
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