The government's commitment to reform social care will require greater investment, ministers have been told.
A bill limiting the cost to disabled and elderly people of their social care will form part of the government's legislative programme for the next year, the Queen's Speech revealed.
Previously ministers had proposed introducing a cap of £72,000 in 2016.
But campaigners and council chiefs told ministers budget cuts were already putting the system at risk.
Research by the Association of Directors of Adult Social Services (ADASS) suggests the £16bn budget for social care, including services for both elderly and disabled people, is likely to be trimmed by £800m in the next 12 months.
It comes after nearly £2bn has already been cut from them in the past two years - despite the prospect of an extra 450,000 people needing state help following the introduction of a cap.
ADASS president Sandie Keene said: "Gazing into the next two years, without additional investment from that already planned, an already bleak outlook becomes even bleaker."
Michelle Mitchell, of Age UK, added: "The legislation announced has the potential to transform our crumbling, unfair social-care system for current and future generations of older people.
"But to have any chance in succeeding we need to see the legislation twinned with a commitment in the spending review for increased spending on social care."
Currently anyone with assets of more than £23,250 faces unlimited costs.
But under the proposed changes, the state will pick up the bill as soon as an individual's costs hit £72,000.
The cap has been designed to protect people against the catastrophic costs that push some into selling their homes.
One in 10 people face costs above £100,000 for old-age care.
As well as paving the way for a cap, the legislation will also change the law regarding social care.
A report in 2011 by the Law Commission said current laws were "outdated and flawed".
There are currently more than 40 different laws that affect social care, but the government is seeking to replace them with a single piece of legislation so people can be clear about their rights.
For example, people with conditions that vary over time, such as bi-polar disorder or dementia, can currently, in theory, be excluded from care because of the contradictory way regulations are written.