The government and the Labour Party are being urged to overhaul England's "failing" social care system, which experts say is leaving 800,000 elderly people "lonely, isolated and at risk".
In a letter published in the Daily Telegraph, a group of more than 60 government advisers, charity directors and independent experts said failure to meet the challenge of an ageing population was resulting in "terrible examples of abuse and neglect".
The signatories, who include representatives from the British Medical Association, Age UK and the TUC, called for cross-party support to secure "urgent, fundamental and lasting reform."
"The unavoidable challenge we face is how to support the increasing number of people who need care," they wrote.
"It is currently a challenge which we are failing to meet - resulting in terrible examples of abuse and neglect in parts of the care system.
"This comes at a huge cost to the dignity and independence of older and disabled people, but also to our society, family life and the economy.
"An estimated 800,000 older people are being left without basic care - lonely, isolated and at risk."
They said some people faced losing their homes and savings because of rising social care bills, while businesses were losing staff who were forced to give up work to care for relatives.
NHS hospitals were "paying the price" because of avoidable hospital admissions, they added.
The signatories backed proposals that no one should pay more than £35,000 for care bills during their lifetime.
According to the BBC, cross-party talks about the care given to the elderly and disabled will resume this month.
A White Paper is due to be published in April.
Care services minister Paul Burstow told the Telegraph the government was "taking leadership on this issue".
He said the coalition agreed the reform of social care was an "urgent priority", adding: "We have put an extra £7.2billion for social care over the course of this Parliament."