Labour leader Ed Miliband has attacked government plans to give more power to family doctors in England.
Speaking at the Welsh Labour conference in Llandudno, Mr Miliband accused ministers of planning to "rip up the NHS" and of being out of touch.
He predicted the plans to hand almost 80% of the English health budget to GPs would provoke a backlash to dwarf that seen over forests.
Health Secretary Andrew Lansley said Labour had no NHS vision of their own.
Previously, Prime Minister David Cameron has said the government was "reforming the NHS so that we have got the best in Europe".
The Health and Social Care Bill, published last month, will allow GPs to get control of most of the NHS budget from 2013 - working in consortiums and taking on responsibility for "buying in" the bulk of hospital and community services for their patients.
In the process, all 151 primary care trusts and strategic health authorities will be disbanded.
Mr Miliband told delegates that ministers knew "the price of everything and the value of nothing."
He argued the government's U-turn over the sale of publicly-owned forests in England was indicative of a broader trend.
Mr Lansley's proposals "bear all the hallmarks of what people dislike most about this government," Mr Miliband said.
"Ideas developed without consultation, ideas that nobody wants, that nobody voted for and that put ideology before the institutions people care about.
"I warn David Cameron and the government: the ill-feeling he created over the forests will be as nothing compared to the real anger that will build about his dangerous plans for the NHS."
The plans have already been denounced by health unions, with critics questioning the timing and whether GPs will have the skills to handle such huge budgets.
Mr Miliband also said the coalition government, in power for nine months, already had "a record to be truly ashamed of", raising unemployment, slowing growth and destroying valued public amenities like libraries and children's centres.
He ridiculed Chancellor George Osborne's claim that the return to negative GDP growth at the end of 2010 was down to unusually heavy snowfall.
"What a feeble abdication of responsibility," he said. "The economic recovery hasn't been hit by the wrong kind of snow. It is being undermined by the wrong kind of government with the wrong kind of priorities."