The Government was conducting final talks with rebel peers in the House of Lords last night in an attempt to head off a series of rebellions that could still derail its Health and Social Care Bill.

Labour will table a series of amendments today which it hopes will win support from Liberal Democrats, who still have concerns about the amount of competition the Bill will impose on the NHS.

Amid signs that Downing Street officials were distancing David Cameron from his beleaguered Health Secretary, senior sources suggested that Andrew Lansley had been lamentable in trying to explain the purpose of his reforms. They fear that even if the Bill is passed without major amendments in the Lords, where it returns today, the reforms will be blamed for all future problems in the NHS.

"The truth is we've given Labour an open goal all the way to the next election," said one government source. "Everything that goes wrong now in the NHS will be blamed on this Bill and there is nothing we can do to stop it." One Downing Street source was even quoted as saying the Health Secretary had failed so badly to explain the purpose of his reforms that he should be "taken out and shot".

The suggestion that Mr Lansley might be forced to resign was roundly denied by Downing Street, which said that Mr Cameron and Nick Clegg had met Mr Lansley yesterday and they had agreed to "press on". Mr Cameron's spokesman said he had full confidence in his Health Secretary.

Yesterday more than 90 per cent of readers of the respected British Medical Journal said they believed the Bill should be withdrawn. But in a sign of the contradictions among opponents, an investigation by The Independent indicates that one of the Bill's most assiduous critics, the chairwoman of the Royal College of GPs Clare Gerada, could gain financially if it were abandoned. Dr Gerada is a partner in one of London's biggest health centres, the Hurley Group, which runs 13 practices across the capital and could suffer from the increased private competition proposed by the Bill. Ms Gerada has condemned the reforms, saying they will result in a "fragmented, expensive and bureaucratic" health service.

But some of her colleagues within the Royal College have questioned whether she is "practising what she preaches" against competition. A statement on her behalf by the Hurley Group said competition could improve the NHS "in the appropriate setting" but "forced competition" in all parts of it would not.

Government sources said last night they believed the 137 amendments to the Bill laid out by Mr Lansley's department last week should be enough to avoid substantial defeats in the Lords.

They said they believed previous Liberal Democrat rebels such as Baroness Williams were now broadly supportive, but that last-minute talks were still going on around the areas of competition.

Labour believes one of its best hopes of a rebellion is over plans to allow hospitals to earn up to 49 per cent of their income from private patients. They will table an amendment restricting this to 5 per cent.

But the Government's position was not helped when the respected health policy think-tank, the King's Fund, stepped up its criticism with its director, Chris Ham, writing in the BMJ that the plan to put doctors in charge of commissioning was "doomed to fail" if they were not given management support.