There needs to be more clarity over a £3.8 billion scheme aimed to integrate health and social care, local government officials have said.
The Local Government Association (LGA) said that the Government needs to commit to the Better Care Fund for a five-year period "to avoid the care system spiralling towards a deeper crisis".
A spokeswoman said there is a lack of clarity over the future of the scheme after the initial first year.
The LGA said that local areas have already pooled £5.4 billion in local Better Care Fund plans for 2015/16, 40% more than the £3.8 billion minimum required by the Department of Health, but it is urging the Government to commit to the joint fund until 2020.
The association has also called for a separate transformation fund to ease the initial impact of the changes.
But it stressed that joint funding for health and social care will provide residents with a better quality of care at home and reduce the need for hospital beds. It will also support people being discharged from hospital, prevent unnecessary admissions at weekends and reduce admissions to residential care.
The initiative, which will draw £1.9 billion of funds from the NHS to support joined-up working between health and social care services from April next year, has drawn criticism in recent weeks.
A report by health think tank the King's Fund said that the financial pressure facing the NHS has been "exacerbated" by the introduction of the f und. And recent reports suggested that the move was to be delayed because Whitehall mandarins said the plans are not credible enough.
LGA chairman Sir Merrick Cockell said: " It is indisputable that in order to improve the lives of older and vulnerable people in this country there is a need for significant changes to the way that social care is funded. A five-year commitment to join up funding between health and social care would provide the certainty and stability required to transform care services for the people who need and rely on them.
"Evidence has shown that integrating health and social care means people will receive better care at home and a reduced need for hospital beds.
"The Better Care Fund is a good start, but it would be short-sighted to expect it to solve the problems of the health and social care system overnight. Health and social care partners have shown their confidence in joining up their funding by putting in additional money over and above what was required by the Department of Health, but despite this there has still not been any indication that funding will be extended beyond this first year.
"Both councils and the NHS are committed to providing the best possible care, so it is vital that we are working closely together with greater ambition and a sense of common purpose if we are serious about making every effort to create a care system that will improve people's lives.
"We are all responsible for making sure that we have a care system that is fit for the 21st century. No one is saying this will be easy. There is less money in the system for everyone, but joining up funding will present opportunities to transform and improve the lives of those using health and care services over the medium and long term at a lower cost."
A Government spokeswoman said: "We welcome the LGA's commitment to joint working. We have already been clear that pooled budgets are likely to be an enduring part of the health and care system, with ministers on the record saying that areas should plan on the basis that this is more than a one-year programme.
"Decisions on future funding will be made at the next spending review in the normal way, but in the meantime, the Better Care Fund is already kickstarting the process of joining up health and social care across the country and areas have a big job to do in making this work from next April.
"Successive governments have talked about integration for decades, but the Better Care Fund is the first serious step towards making this a reality and transforming the lives of people who use health and care services."