Firefighters in North Yorkshire say they are concerned at plans by bosses to make up to £4m in savings.
The proposal was announced by the county's fire service ahead of the spending review on Wednesday.
Members of the Fire Brigades Union (FBU) are worried jobs will be lost. They are also unhappy about proposals for a new fire station in York.
A North Yorkshire Fire and Rescue Service spokesman said front-line services would not be affected.
FBU members were in the centre of York on Wednesday, asking members of the public to sign a petition as part of their "Cuts Cost Lives" campaign.
Branch secretary Ian Watkins said firefighters had been told the service was considering voluntary redundancies, but they believed further posts may go.
He added that they were also concerned about plans for a £4.5m fire station on Kent Street, at a time when they should be ensuring the future of their workforce.
A North Yorkshire Fire and Rescue Service spokesman said: "The front line fire service which we provide to the public will not be affected."
He added that the new station would help improve fire crew response times in and around York.