"Tribal politics" is failing to find solutions for the crisis faced by the NHS and social care, with patients "too often" failed by a system under strain, a group of 90 MPs have said.
Dozens of MPs, including six former cabinet ministers and several Conservatives have called for a cross-party convention on the future of the NHS and social care.
In a letter to Theresa May and Chancellor Philip Hammond, the MPs said action is needed as NHS patients and those needing care are "too often failed by a system under considerable strain".
The convention would work on a cross-party basis, engaging with the public and the health and care workforce to confront the mounting pressures in the system arising from an older population and growing demand for healthcare.
The group, which includes 22 former ministers, also urged Mr Hammond to find more money in next week's Budget to address short-term pressures in the system.
Conservative Health Committee chairwoman Sarah Wollaston, who organised the letter alongside Liberal Democrat former care minister Norman Lamb and Labour former shadow care minister Liz Kendall, said any move by Mr Hammond to lift the public sector pay cap for NHS workers must not be funded by raiding existing health budgets.
And calling for a cross-party convention, she said: "The funding and workforce challenges facing our NHS and social care services are immense.
"Finding a long-term, sustainable solution must be raised up the Government's domestic agenda.
"The public want to see this resolved and this letter demonstrates the willingness of politicians to work constructively across party lines to make it happen."
The Government ditched plans for a so-called "dementia tax" to fund social care after it proved unpopular during the general election in which the Tories unexpectedly lost their parliamentary majority.
This week ministers announced they would bring forward a green paper on the future of social care funding by summer 2018.
But the MPs said a convention would would "give hope" to the public and health and care staff who have "real anxieties" about the future sustainability of "vital" services.
Mr Lamb said: "Tribal politics has failed to provide a solution to the existential challenges facing the NHS and social care.
"We know that the current situation is unsustainable, and these pressures will only get worse as we contend with an ageing population and rising demand for care and treatment.
"This letter shows the strength of cross-party support for a new approach based on co-operation instead of political point-scoring.
"The fact that so many senior MPs and former cabinet ministers support this initiative is remarkable. Now the Government must act on it."
Ms Kendall said: "Our population is ageing, more people need help and support and our care services desperately need more money to cope, yet any party that comes up with a significant proposal for funding social care risks their political opponents destroying them.
"We could carry on like this for yet another Parliament, and yet another election, or we could face up to reality: we will only get lasting change if we secure a cross-party approach."
Speaking on Saturday, Ms Wollaston said the Chancellor must find extra money for the NHS and should not fund an expected pay rise for health workers from existing budgets.
She told BBC Radio 4's Today programme: "In the short-term we need a down payment of £4 billion really and we cannot, cannot have an uplift in public sector pay from the existing budget arrangements because as we are in this current financial year, we're set to see a fall per head in funding."