Chairs of three influential House of Commons committees have issued a plea for Theresa May to call a cross-party review of the health and social care systems.
In a letter to the Prime Minister, the trio - Conservative MP Sarah Wollaston of the Health Committee, Labour's Meg Hillier of the Public Accounts Committee, and the Communities and Local Government Committee's Labour chair Clive Betts - said that political consensus was needed to find a long-term solution to the "pressing" social care challenges facing the country.
They called on Mrs May to invite all parties to take part in an "urgent" review taking in not only the financial sustainability of the social care system but also the NHS, to be completed in time for an agreed approach to be reflected in the next Government spending round.
The letter came two weeks after the three chairs directly addressed Mrs May on the need for a review during her appearance before the Commons Liaison Committee on December 20.
Mrs May agreed then that previous governments had "ducked" the issue of social care funding and said she was determined to ensure a sustainable system for the future.
She said that it would be "for everybody to contribute and to be part of that decision", but appeared to pour cold water on the idea that the best way to ensure consensus was a cross-party review, telling Dr Wollaston: "Past experience does not suggest that that is the case."
In their letter, the three MPs told Mrs May: "We were encouraged by your recognition at the Liaison Committee that everyone has a part to play in finding a sustainable way of ensuring social care provision in the future. You also accepted the need for a review to find a way of funding social care sustainably for the long term.
"We believe that can best be achieved if there is cross-party consensus, and therefore urge you to invite all parties to become involved in a review, which should begin as soon as possible.
"Given the scale of rising demand, this immense challenge will face whichever party is in government over the coming decades."
They added: "The ongoing separation of health and social care is creating difficulties for individuals and avoidable barriers and inefficiencies. Any review should cover the two systems."
Chris Ham, chief executive of health think-tank The King's Fund, said the "threadbare" social care sector was facing a £2.4 billion funding gap, while planned increases in health funding were "not enough to maintain standards of care, meet rising levels of demand, and transform services".
"A new settlement for health and social care is long overdue," said Professor Ham.
"For too long there has been a lack of political leadership on these issues. We agree with the committee chairs that a political consensus that puts health and social care funding on a sustainable footing is sorely needed. Without a consensus, patients and people in need will suffer."
The chairman of the Local Government Association's Community Wellbeing Board, Izzi Seccombe, backed the call for cross-party agreement and said it was "absolutely vital" that council leaders with responsibility for social care provision are included in any review.
"We completely support the select committees in urging the Prime Minister to reach a cross-party agreement on the future of health and social care funding," said Ms Seccombe.
"Following last month's Local Government Finance Settlement, we said there needed to be an urgent and fundamental review of social care before the spring Budget, and we are pleased the select committees back this."
GMB union national officer Sharon Holder said: "Health and social care funding is arguably the most pressing issue facing our country - with a crisis of epic proportions looming in the very near future.
"GMB welcomes this new pressure on Theresa May to confront the problem rather than burying her head in the sand - or passing the buck onto local authorities."
Janet Morrison, chief executive of the charity Independent Age, said: "The calls for a long-term solution on health and social care funding are now overwhelming. The Prime Minister must heed these calls and take urgent action to establish a cross-party process that will come up with recommendations on social care.
"We have long argued that any long-term solutions must be above party political divisions, as the challenges in social care will affect people for years to come. The Prime Minister must grasp this opportunity to ensure this process brings change that ultimately improve the lives of millions of older people who rely on adult care services now and in the future."
A Government spokeswoman said: "We recognise the pressures of an ageing population which is why we recently announced almost £900 million of additional funding for adult social care over the next two years.
"This Government has gone further to integrate health and social care than any other before it. We have brought budgets together for the first time through the Better Care Fund and given the NHS an extra £10 billion per year by 2020/21 to fund its own plan to build a more responsive, modern health system.
"But as the Prime Minister has made clear, this is not solely about money. That is why we are working to find a long-term, sustainable solution which helps local authorities learn from each other to raise standards across the whole system."