Devon and Cornwall Police has been named as one of three police forces which may not be able to provide an efficient or effective service for the public in the future.
The judgment came in a report by Her Majesty's Inspectorate of Constabulary (HMIC).
In our professional judgment (and having considered local context, including police cost to the taxpayer), there is a risk that three forces may not be able to provide a sufficiently efficient or effective service for the public in the future.
Lincolnshire and the Metropolitan Police were the other forces named.
Almost 6,000 fewer officers will be on the policing frontline in three years' time as a result of the Government's budget cuts.
The number of non-frontline officers is almost halved, with 7,600 going by 2015, the report said.
Some 137 police access counters, such as in libraries and supermarkets, will also open to help offset the closure of 264 front desks.
The figures do not include those for Britain's biggest force, the Metropolitan Police, or for Cheshire, as they have not yet produced their plans.