The government has cut the funding for its proposed overhaul of adult social care by 58%, according to a report from the National Audit Office (NAO).
The watchdog said that despite being just two years into the 10-year scheme, plans to cap the cost of lifetime care had been delayed and other proposals had been scaled back, with even revised policies falling behind schedule.
The NAO said over £1bn of the £1.7bn allocated by the Treasury for the reforms had now been "diverted to other care priorities", with the cash being "reprioritised... in favour of helping to stabilise the sector", as soaring inflation continued to "compound long-standing pressures".
A Department of Health and Social Care (DHSC) spokesperson insisted ministers "remain committed to reform".
But Labour said the report "makes clear that the Conservatives will break their promise to 'fix the crisis in social care once and for all' by the next election".
The Liberal Democrats said it showed a "chronic neglect of adult social care" under the Tories.
In its report, the NAO pointed to the ministerial decision last autumn to postpone putting £3.6bn into cost reforms, and instead commit up to £7.5bn to the care sector.
That included £2.7bn to dish out to local authorities to help ease immediate pressures - something the watchdog described as "welcome relief".
But it warned funding "may not be reaching areas that need it most", with the government having failed to update its formula for distribution since 2014 - meaning up-to-date local variations in need hadn't been taken into account.
According to figures from the DHSC, one in six councils expected demand for adult social care to exceed capacity over the coming winter.
The NAO said there had been "recent signs of improvement" in adult social care, but overall it remained "under significant pressure", with double the number of people waiting more than six months for a care assessment in March 2023, compared to the end of 2021 - around 82,000.
And vacancies in the sector still stand at around 152,000 - an equivalent of 10% of the workforce.
The watchdog said that, despite there being "much to do" for the government to achieve its 10-year goals, the DHSC had no "overarching programme to coordinate its reforms, making it difficult to know if it is on track to achieve its objectives", and no "long-term funded plan for transforming adult social care".
It called for the department to assess the impacts of its current plans and set out how it intends to fund its future ones.
"Adult social care reform has been an intractable political challenge for decades," said Gareth Davies, head of the NAO.
"Government has set out its ambition to meet this challenge and now needs to demonstrate how it is delivering on these plans."
He added: "If [the] government is to successfully reform adult social care, it will need to manage some significant risks, including its own capacity and that of local government to resume charging reform activity alongside system reform.
"To maximise its chances of succeeding, [the] government will need to ensure it understands the impact of its ambitions on local authorities and other stakeholders and establish a costed plan which ensures delivery of its long-term goals."
A spokesperson for the Labour Party said: "This report makes clear that the Conservatives will break their promise to 'fix the crisis in social care once and for all' by the next election.
"Delays and watered-down workforce reforms will leave the sector without the care workers it needs. People will wait longer and longer for care, as there simply aren't enough staff."
Lib Dem health spokesperson Daisy Cooper added: "This damning report shows the chronic neglect of adult social care under this Conservative government.
"The shockingly dismal state of care is putting huge pressure on the NHS while leaving the elderly and vulnerable to suffer."
Ms Cooper also accused the Tories of having "repeatedly broken their promises on social care and delayed proposals for a lifetime cap on care costs".
But a DHSC spokesperson: "We remain committed to reform, and are investing up to £700m over this year and next to make major improvements to the adult social care system.
"This includes £42.6m to support innovation in care and increasing the Disabled Facilities Grant by £50m.
"Additionally, we have made up to £8.1bn available to help local authorities tackle waiting lists, low fee rates, and workforce pressures, £570m of which will help local authorities improve adult social care provision, in particular by boosting the workforce."