Police officers' jobs could be saved if more support posts were cut, a Police Federation spokesman has said.
Plans have been approved to save Devon and Cornwall Police £47m over four years - which could see 700 officer and 500 civilian support posts lost.
Federation spokesman Nigel Rabbits said sworn officers should be more protected than "bureaucratic" posts.
His comments were criticised as being "offensive and insulting" by the union which represents civilian police staff.
In an interview with BBC News Mr Rabbits said Devon and Cornwall already had sparse numbers of officers.
"We have real concerns about how the 'thin blue line' can be maintained," he said.
"Policing is about sworn police officers. There must be still some people who are working in the organisation who are just providing a bureaucratic function."
Bob Waycott, of Unison, said civilian staff were "very dedicated" people who worked tirelessly to support both police officers and members of the public.
He said to suggest they only perform a bureaucratic function was "very wrong and very harmful".
"I find the remarks made by Nigel Rabbits offensive and insulting to police civilian staff," Mr Waycott said.
"At difficult times like this the unions and the federation should be working together."
The 20% reduction in officers' posts from about 3,500 to 2,800 would see staffing levels cut back to those of 2004.
But Chief Constable Stephen Otter said the ratio of post closures being proposed was right and cutting more civilian posts was not the right thing to do.
"We've been very successful in getting police staff to do jobs that actually release officers to the front line.
"Over the last two or three years we've released another 200 officers by civilianising jobs at a much lower cost.
"If we were to change the balance of the reductions, we would end up taking more and more of our officers off the streets and back into administrative jobs that are currently done by police staff."