The main medical unions have declared all out opposition to the government's health Bill.
Both the Royal College of Nursing (RCN) and the Royal College of Midwives (RCM) have called for the Bill to be scrapped.
It follows a move by the British Medical Association (BMA) in December to also fully oppose the Health and Social Care Bill, currently going through Parliament.
The RCN, which is the biggest nursing union, said "serious concerns" have not been addressed during the parliamentary process, listening exercise or political engagement.
The union said the Bill will not deliver on the principles originally set out.
Recent announcements such as the rise in the cap on private patients being treated in NHS hospitals to almost half (49%) "make the Bill in its entirety a serious threat to the NHS", it said.
Dr Peter Carter, chief executive of the RCN, said: "Opposing this Bill is not a decision we have taken lightly - we have worked hard on behalf of all our members to influence the decisions that have been taken as the Bill has gone through Parliament.
"However, it is now clear that these 'reforms' are forging ahead on the ground - without the concerns of nurses and other clinicians being heeded.
"We have sought a range of assurances, but now feel that the reforms as they stand could have the opposite effect from that which was intended."
Dr Carter said the reforms were occurring at a time when the NHS has been tasked with saving £20 billion by 2014.
"The RCN has been on record as saying that withdrawing the Bill would create confusion and turmoil; however, on the ground, we believe that the turmoil of proceeding with these reforms is now greater than the turmoil of stopping them.
"The sheer scale of member concerns, which have been building over recent weeks, has led us to conclude that the consequences of the Bill may be entirely different from the principles which were originally set out.
"The RCN feels that these concerns are so fundamental that we must now oppose the Health and Social Care Bill."
RCN research has shown that 48,000 NHS jobs in England have been lost or face the axe.
Dr Carter said: "Patient care is undoubtedly being put in jeopardy.
"With this in mind, the RCN proposed an amendment to the Bill which would guarantee safe staffing levels, but the government chose not to take this proposal forward.
"Without these checks and balances, and a commitment to regulate the healthcare assistants who are so crucial to the delivery of care, these reforms could damage the very system they were designed to improve."
On the issue of hospitals being able to make up to half their income from private patients, Dr Carter said: "While we are not opposed to the principle of competition in the NHS, recent developments have shown that the balance between competition and quality has become skewed."
The RCM added that the Bill was "divisive and costly".
RCM chief executive Cathy Warwick said: "This Bill is a massively expensive distraction from the challenges that the NHS faces in trying to improve healthcare at a time of severe spending restraint.
"The Royal College of Midwives supports many of the government's aspirations for the NHS, such as clinically-led commissioning, greater engagement of service users in their care and more integrated services, but the fact of the matter is that these can all be achieved without the need for this divisive and costly Bill.
"Independent analysts have calculated that implementing the provisions in the Bill will cost the NHS an extra £2 billion to £3 billion on top of the £20 billion in efficiency savings the NHS has to find in the next four years.
"The government has failed to present sufficient evidence that its proposals are necessary. They have failed to present evidence that the upheaval will result in an improvement in services to the people of England. And, they have failed to answer the concerns of the people who fear for the future of the NHS under these plans.
"Breaking up what we have, embracing the private sector, and injecting full-blown competition and market forces is not what the NHS needs or what health professionals and patients want.
"We join the growing chorus of voices calling for the Bill to be withdrawn, and the proposed reforms stopped in their entirety."
A spokeswoman for the BMA said: "We are pleased that the RCN and the RCM have moved to a position that reflects our own and will continue to work with them with the aim of getting the government to drop this flawed Bill."
A spokeswoman for the Department of Health said: "We're disappointed that these Royal Colleges have come to this position.
"During the course of the past twelve months we have been working with nursing groups to shape our plans for a modern NHS. For example, nurses will be represented on local clinical commissioning groups.
"Just two weeks ago, the Prime Minister set out plans welcomed by the RCN to get rid of red tape so that nurses have more time to spend with their patients.
"The RCN has conflated the Health and Social Care Bill with issues about the need for the NHS to spend its money more efficiently. The Bill is needed to empower doctors, nurses, and other frontline healthcare workers across the NHS to take charge of improving care.
"We will continue to work with nurses and all other health professionals to ensure that the NHS delivers the best possible care for patients."
Shadow health secretary Andy Burnham said: "It's hard to see how David Cameron can carry on with his Health Bill after the decisions taken by the Royal College of Nursing and the Royal College of Midwives.
"Doctors, nurses and midwives are now standing together in outright opposition to his plans to turn the NHS into a market-based system.
"A reorganisation on this scale needs a professional consensus for it to succeed. A year since the Bill was introduced it is abundantly clear that the government's plans have failed to build that.
"We agree with the RCN's assessment that the risks of proceeding with these plans are greater than the risks of dropping the Bill.
"It is time to put the NHS first. The government must listen to patients and NHS staff and put this Bill out of its misery."
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