David Cameron has been warned by a group of leading charities that pensioners could face a life of "misery and fear" without reforms to social care.
A coalition of 78 charities and campaign groups have told the Prime Minister in an open letter to the Daily Mail that a postcode lottery of access to care is leaving many elderly people in "quiet desperation".
Under the current system, pensioners have to pay the cost of their own care if they have savings or assets worth more than £23,500.
The charities have pleaded with Mr Cameron to make social care reform his "personal mission" and said there was widespread support "across society and the political spectrum".
The letter comes ahead of this week's Queen's Speech, with some groups fearing it will not include a Bill on social care.
The letter, which has been signed by Age UK, Saga and the Local Government Association, reads: "Social care is in crisis - the system is chronically underfunded and in need of urgent reform.
"Without this, too many older and disabled people will be left in desperate circumstances: struggling on alone, living in misery.
"The system is a lottery - some of us will be lucky enough never to need care, but there are many of us who need support at some stage in out lives to carry out everyday tasks and could lose everything: our savings, our dignity, our independence.
"That is why we are calling on you to take forward social care reform as your personal mission."
A White Paper on long-term care will be published in June, but it will focus on the quality of care provision, with the issue of paying for it relegated to a "progress" document.