Shadow chancellor John McDonnell says the government’s Budget has offered “nothing” to tackle the “social care crisis”.
He told the BBC it would be difficult to “rebuild” social care services to cope with the coronavirus outbreak.
He said he was “worried” about the future, but he welcomed extra funding to help the NHS.
Health Secretary Matt Hancock said social care will get “everything it needs” to respond to the outbreak.
Earlier, Chancellor Rishi Sunak announced at least £5bn this year for the NHS in England to help it cope with the spread of the virus.
Mr Hancock told MPs the extra cash was for “social care too”, telling MPs that adult social care “will be at the front line of our response”.
It comes after Mr Hancock wrote to MPs last week to start cross-party talks to find a long-term solution on how social care should be funded.
The talks were a pledge in the Conservative election manifesto, which also promised an extra £1bn per year for social care in England over the next five years.
According to NHS Digital, 841,850 people were receiving long-term care in England in 2018. An ageing population is expected to increase demand.
Speaking on the BBC’s Andrew Neil Show, Mr McDonnell said he would support any “effective” plan to emerge from the talks.
But he accused ministers of having failed to “seriously” acknowledge pressures faced by the sector, and failing to “learn the lessons” from budget cuts to public services over the last 10 years.
“There’s nothing for social care today,” he added, referring to the Budget.
“If you don’t tackle the social care crisis, we’re going to have real problems – not just immediately but for the long-term future”.
Earlier, former Conservative health secretary Jeremy Hunt admitted he failed to solve issues relating to social care whilst in office.
Writing on Twitter, he added that the sector “desperately” needed a long-term plan to go alongside the 10-year NHS England blueprint unveiled last year.
“Hospitals will continue to fill up, and the winter crisis will be annual until we fix this issue,” he added.
Speaking after the Budget was delivered, acting Liberal Democrat leader Sir Ed Davey said the spending plans did not do “anything” for social care.
“We have a care sector on its knees. Care homes are closing and there are shortages of care staff,” he said.
“It is an astounding omission.”
Siva Anandaciva, chief analyst at the King’s Fund think tank, said adult social care remained a “pressing and overlooked” issue.
He added that it was “hugely disappointing” the Budget “does not include an emergency cash injection to help local government to address social care needs beyond coronavirus.”
Social care is a devolved issue. In Scotland, the SNP has said if it is re-elected in 2021 it would scrap all non-residential social care charges.
Plaid Cymru has said social care in Wales should be free at the point of need and funded from general taxation.