Fresh cuts to police budgets could lead to "dramatic and dangerous" variations in services, a senior officer has warned.
Some forces will struggle to find the savings required under new financial arrangements which will be confirmed by the Government later this year, according to Chief Superintendent Irene Curtis.
Ms Curtis, president of the Police Superintendents' Association of England and Wales (PSAEW), is the latest figure to issue a warning to Home Secretary Theresa May about the impact of possible cuts.
The officer said: "I do not believe that individually every force can find the savings that will be needed.
"Even working collectively, I do not believe that 43 forces together will be able to meet the savings targets without it potentially leading to dramatic, unfair and dangerous variations in the level of service provided from one force to the next, and the loss of public confidence that will inevitably result."
Mrs May's department, which is responsible for handing out money which makes up the majority of police budgets, has been told to prepare proposals that would achieve savings of 25% and 40% by 2019/20.
The Home Office has said no decisions have been taken on police funding beyond the current financial year.
Last week the Association of Police and Crime Commissioners (APCC) published an analysis of the possible consequences on the police service of potential cuts over the next five years.
It said uniformed officers may have to take on back office roles and the size of the total force in England and Wales could fall below 100,000 by the end of the decade.
Ms Curtis, whose organisation represents senior operational police leaders, said decisions on police budgets should not be seen in isolation from spending on other public services.
Speaking ahead of the PSAEW's annual conference, she said: "The cuts that policing is facing are too great, and the impact they will have should no longer be considered to be just policing's problem. I think they are a problem for everybody to face, not only the police service, but also government, our public sector partners and particularly the public, who are, after all the main recipients of policing services.
"Because if we cannot police effectively with the resources we have with, that becomes a problem for society. I genuinely believe that the scale of the challenge ahead makes this a serious risk."
She called for a "radical rethink" of how public service are funded and delivered.
"If this isn't addressed, then the next round of cuts will have a fundamental impact on all public services," she said. "Almost everything that the police deal with today has an impact on, a crossover with, or a root in another public service; whether that is health, education, social services, housing or something else.
"Government cannot look at policing budgets or services in a silo any more. We need to think differently about how public services can be delivered better, in a more integrated way that reduces future demand everywhere."