Health chiefs have said the Government's controversial NHS reforms are a "distraction" from confronting £20 billion budget savings and long-term care for the elderly.
The warning came as it was reported an influential cross-party group of MPs plans to heavily criticise the revamp of how health services are provided in England.
But ministers vowed to press on with changes, which have already been diluted from original proposals, amid calls from the Royal College of Nursing and the Royal College of Midwives to scrap the Health and Social Care Bill.
NHS Confederation chief executive Mike Farrar said: "From the outset, we have made clear the Government's reforms to the administrative structures of the NHS are a distraction in terms of addressing these fundamental challenges. We are therefore increasingly worried by the lack of clinical support for the reforms and the fact clinical opposition to the changes has hardened in recent days.
"This is a major risk. We have always said that buy-in from healthcare professionals is the key to delivering a workable set of reforms. We need some pragmatism and realism, along with the politics, if we are to steer the NHS through these incredibly choppy waters."
The Observer said the Commons Health Committee would this week claim Health Secretary Andrew Lansley's shake-up was obstructing efforts to make the NHS more efficient.
The newspaper said the committee, chaired by Conservative former health secretary Stephen Dorrell, had concluded the plan to restructure the NHS and devolve more power to GPs was making it more difficult to hit efficiency savings by 2014-15.
Labour branded Mr Lansley's reforms a "monumental mistake" and demanded a rethink. Shadow health secretary Andy Burnham said: "This report is a damning indictment of the Government's mishandling of the NHS."
But Deputy Prime Minister Nick Clegg warned the coalition could not "stick our head in the sand and say 'no change'".
He said: "People shouldn't think the best way to cherish and preserve everything that we love about the NHS is somehow to freeze it in time and then it will all be OK. Our view is that these reforms, by making people in the frontline more responsible for use of NHS money, actually help make the savings, not hinder it."