Questions have been raised about potential job losses if Chorley pulls out of Lancashire County Council.
Chorley Council leaders announced this week that they would like to go it alone as a unitary authority.
Residents would be asked to vote in a referendum, possibly as soon as next May.
But trade unions are concerned this could lead to job cuts in Lancashire.
Elaine Cotterell, branch secretary for Lancashire Unison, said: “I will be seeking a meeting with the council leader at the earliest opportunity. Clearly, it’s a cause of concern, because I remember back in 1998, when we went through the process of creating unitary authorities in Blackpool and Blackburn, and hundreds of jobs were lost.”
She fears the proposal will cause more “uncertainty” for staff, as the county council already looks to save money.
She added: “There is enough uncertainty among the Lancashire County Council workforce without this on top.”
But Coun Alistair Bradley, leader of Chorley Council, said staff would be needed if it became a unitary authority.
He said: “It is very early days so no plans have been made yet, but we would obviously need additional people to take on the responsibilities, if we did become a unitary authority.
“There are likely to be job losses at the county council regardless of this proposal as they have said they have a £330m budget gap to fill.”
Jennifer Mein, leader of Lancashire County Council, said: “Economic growth and job creation are amongst our top priorities and they depend on collaboration across large areas that can determine and develop big strategic matters like transport infrastructure, not small areas working in greater isolation.”