Firefighters working for Avon Fire and Rescue could be asked to go part time after the service's budget was cut by £2.3m.
Avon Fire Authority met on Friday to discuss how to implement a drop in funding from the government.
John Drake, from the Fire Brigades Union (FBU), said the plan was "one measure in a range of measures".
Terry Walker, chairman of the Avon Fire Authority, claimed there would be no cuts in frontline services.
"The number of appliances, the number of fire stations and the number of appliances will be maintained," he said.
"We have to look at a smarter way of working. We've got to look at sharing principal officers, we've got to look at sharing back-up services.
"We can't afford to keep all of the back-up to the people that we've got at the moment.
"We've suffered cuts under the previous government and now we're suffering a terrific cut this year."
The £2.3m of cuts which Avon Fire and Rescue has to make represents about 9% of the service's budget.