The government has been heavily criticised over controversial plans to allow private companies to take over the management of struggling NHS primary care trusts.
Health campaigners accused ministers of opening the door to private firms to make "mega bucks" from the taxpayer, and pledged to seek support from MPs and unions to fight the proposals.
Health minister Ben Bradshaw said bringing in private firms was one of a range of options aimed at improving performance, and insisted that no NHS assets or staff would be transferred to private companies.
But leaders of nurses, doctors and other health workers hit out at the announcement and said they would build a campaign of opposition.
"The BMA would have grave concerns if the private sector took over the management of NHS trusts. Such a move would effectively see parts of the NHS become privatised," said Dr Jonathan Fielden of the BMA.
"There is an immense amount of talent within the NHS, and this should be nurtured, grown and developed to ensure NHS trusts do not find themselves in a position of failure in the first place."
Paul Kenny, general secretary of the GMB union which represents NHS staff, said his union would "resist this move with every sinew".