Labour has made plans to mount a last-ditch bid to block the Government's NHS reforms as the House of Lords prepares to pass the legislation.
The Lords is due to give the Health and Social Care Bill its third and final reading on Monday night, possibly the last opportunity for opponents to prevent the reforms becoming law.
But shadow health secretary Andy Burnham is to use a special parliamentary procedure to ask Speaker John Bercow for an emergency debate in the Commons on Tuesday. He will demand that the Bill does not become law before the Government has published its risk assessment of the reforms.
Former SDP leader Lord Owen is also spearheading an attempt in the Lords to defer the third reading until parliament has seen the risk register. He has tabled a motion that shadow leader of the Lords Baroness Royall told fellow peers they had a "duty" to support.
In a blogpost on LabourLords.org.uk, Baroness Royall said: "Today (Monday) is a critical day for the NHS. It is a day on which the Lords will have up to two final opportunities to have an impact on the future of the Health and Social Care Bill, a day on which because of the coalition majority in the Commons, the fate of the NHS will pretty much be sealed."
The Labour peer said that if Lord Owen's motion failed, then the third reading should be refused by the Lords.
She said: "As we know, the vast majority of health and social care professionals as well as the general public are against this Bill, as it will exacerbate the problems they are already experiencing as a result of the Nicholson challenge. But the coalition is determined to plough its ideological furrow regardless."
The British Medical Association (BMA) also urged the House of Lords to block the Health and Social Care Bill.
Dr Hamish Meldrum, chairman of the BMA Council, said: "Even at this late stage a number of peers are raising very serious concerns about this Bill, which are shared by the BMA. Today is the last chance for peers to stop it and we would urge them to do the right thing - it is still not too late.
"The Health and Social Care Bill is not fit for purpose and it would be far better for the NHS if it were withdrawn. We want the Government to work with healthcare professionals so an alternative solution can be developed, one which has the support of NHS staff and the public."