Local authorities could be allowed to make a further increase in council tax to pay for social care.
Ministers in England are discussing ways to invest more money into care services for the elderly and disabled.
Lib Dem health spokesman Norman Lamb called for a cross-party commission on social care to ask the public how much they are prepared to fund the service.
“If you keep sleepwalking towards the edge of the precipice, real people will suffer,” Mr Lamb said.
Communities Secretary Sajid Javid will unveil spending plans on Thursday.