The House of Lords is to vote on plans that ministers say could kill off the government's health bill for England.Peers will decide whether to delay the bill, which would give clinicians control of budgets, and refer parts of it to a special select committee.Health Minister Earl Howe has warned that a hold-up could "prove fatal" to the entire Health and Social Care Bill.Peers will also vote on an amendment by Labour peer and former GP Lord Rea to block the bill altogether.He argues it was never a manifesto commitment by either the Conservatives or the Liberal Democrats.The Health and Social Care Bill would increase competition and put GP-led groups in control of buying care in their areas.Ministers say the changes are vital to help the NHS cope with the demands of an ageing population, the costs of new drugs and treatments and the impact of lifestyle factors, such as obesity.They say the bill, which has already been substantially altered following criticism from NHS staff and Liberal Democrat MPs, now has wide support.But leading medical professionals have warned that the proposals are still unpopular."Choice is fine but to have choice ahead of quality and delivering consistent healthcare, seamless healthcare for patients, is going to result in a chopped-up health service with little bits competing with other little bits," Dr Laurence Buckman, a senior representative from the British Medical Association, told BBC Breakfast.On a second day of debate in the House of Lords, two crossbench peers - Lords Owen and Hennessy - have tabled an amendment calling for part of the bill to be sent to a special select committee, which allows witnesses to give evidence, for further scrutiny.They say the bill raises serious constitutional issues, particularly aspects relating to the role of the health secretary in overseeing the NHS and the role of a new body, Monitor, in promoting competition within it.Lord Owen said a special select committee was the only way of looking at "the complexity of this new relationship we are trying to establish" between patients and clinicians."Health is not a public utility," he warned. "Health is different."Labour peers are expected to back Lord Owen's amendment when the house votes later on Wednesday morning and they could be backed by Lib Dem rebels unhappy about the bill.Baroness Thornton, who leads for Labour on health in the Lords, said the bill would turn "patient choice into shopping", while healthcare would become a "traded commodity".For the government, Lord Howe, told peers the proposed changes would "liberate the NHS" and improve patient care in England.He said any further delay at this stage could risk the entire legislation - which ministers want to become law by the end of the current parliamentary session next April."The House must have proper time to examine the bill but the proposal put forward by Lord Owen could result in delay, which could well prove fatal to it," he said.And former health minister Lord Darzi, who wrote a report on the future of the NHS for Gordon Brown, has said the health service "must embrace change" or risk "falling back".