A compulsory levy should be introduced to fund a universal social care system for adults in England, Labour says.
It said the move would represent the biggest shake-up in the welfare state since the creation of the NHS and end the "cruel lottery" currently in place.
But ministers refused to be drawn on how much and when people should pay, saying a commission would be set up to look at this if they win the election.
Such a charge is opposed by the Tories, who have dubbed it a death tax.
The subject is now likely to become a key issue during the election campaign.
The current system for providing support to the elderly and people with disabilities is means-tested.
So if Labour's plan for a National Care Service were introduced - and this would not happen until after the lifetime of the next parliament - it will be the first time everybody has been entitled to state support for a residential care place or home help.
The intervention comes after councils have been struggling to cope with rising demand, mainly fuelled by the ageing population.
WHERE THE PARTIES STAND
Labour - Put forward three proposals last summer and after public consultation has now backed a compulsory levy, although commission to be set up to decide how much and exactly when people should pay
Tories - Proposed an £8,000 voluntary insurance model to cover residential care costs. Now drawing up plans for a voluntary scheme to cover domestic care, such as help washing, eating and dressing in the home
Lib Dems - Initially supportive of free personal care - like Scotland has introduced - but now want a "partnership" whereby state pays some and individual tops this up. Open to compulsory levy
But cross-party talks in recent months failed to reach a consensus.
The Conservatives are adamant people should not be compelled to pay and refused to back a compulsory levy in talks held in recent months. Instead, they back a voluntary insurance scheme.
However, Health Secretary Andy Burnham said making everyone pay - apart from the very poorest - was the only fair way to create a fair system as he unveiled a white paper on the issue.
He announced an independent group of experts would be appointed to look at exactly how such a fee could be applied. This will look at a range of methods, including allowing people to defer their pensions, paying it up front or taking it from their estate after death.
Mr Burnham hailed the policy as a "momentous decision".
Pensioner Audrey Burgin: "People say I could go on a world cruise for the money I spend on care"
He added: "It will give people peace of mind in later life and help them protect everything they have worked for. We have the cruellest system of all at the moment."
As an interim measure, the government has already said it will provide free care in their own homes to people with the most severe needs.
People who have been in care homes for more than two years will get their care for free from 2014 as part of a phased introduction of the new system.
Campaigners welcomed the move, saying it would benefit the most vulnerable people in society.
Stephen Burke, chief executive of Counsel and Care, the charity for older people, added: "Free care for all is a historic commitment and signals a new frontier to the welfare state."
'Must sort this out'
But shadow health secretary Andrew Lansley accused ministers of still wanting a death tax but just delaying the decision for a few years.
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