The Government's plans for the NHS introduce "significant institutional upheaval" without really changing its aims, according to a damning report from MPs.
Ministers have failed to show the plans represent the most "efficient" way of delivering good patient care, while some risks to the health service will increase, said the cross-party Commons Health Committee.
MPs said they were "surprised" by the "significant policy shift" between what the coalition promised to do in May and the plans set out in its health white paper in July.
The coalition programme outlined an "evolution" of existing bodies in the NHS but the white paper "proposes a disruptive reorganisation of the institutional structure of the NHS which was subject to little prior discussion and not foreshadowed in the coalition programme".
Such a surprise, while not necessarily wrong, increases the risks to implementing policy, and risks not fully engaging staff, the MPs' report said. While supporting the objectives for the health service, the MPs said the priority for the NHS was to find £15 billion to £20 billion in "efficiency savings", as ordered by NHS chief executive David Nicholson.
This is already something that is "extremely challenging" and so the failure to properly plan for upheaval in the NHS is of "particular concern" in the current financial context. "The Nicholson challenge was already a high-risk strategy and the white paper increased the level of risk considerably without setting out a credible plan for mitigating that risk," the MPs said.
The report comes ahead of Wednesday's publication of the Health and Social Care Bill which details a radical overhaul of the NHS, with most of the NHS budget passing to GPs, who will take control of commissioning services for patients.
Tory MP Stephen Dorrell, chairman of the health committee, said it was vital that a wide range of health professionals was involved in the reforms, not just GPs.
He said: "The Government proposals clearly engage GPs in commissioning and that's a key step forward ... but in the view of the committee it can't just be GPs, it has to be GPs as a catalyst for the wider community."
He said the committee was acting as a "critical friend" to the Government, and shared the objectives of improving patient care. "We are not grandstanding but we are not patsies," he added.