Labour took the unprecedented step of moving to kill off coalition NHS regulations in the Lords today, amid growing anger at perceived moves to privatise the service.
Andy Burnham said the exceptional nature of the Section 75 regulations, which force all NHS services out to tender, meant he needed to table a 'fatal' motion in the second Chamber.
"We have got a matter of weeks to prevent the NHS being sold to the lowest bidder," he said.
"Ministers' promises to 'let doctors decide' are rendered worthless by regulations mandating compulsory competitive tendering across the NHS. What they failed to achieve by the front door, they are now trying to sneak through by the back door."
The Section 75 regulations mean all NHS services must be opened up to competition from private firms and voluntary groups. This puts the system under EU procurement law, which enforces competition rules.
Shadow health minister Lord Hunt of Kings Heath said: "These regulations do not accurately reflect the assurances that health minister Earl Howe gave the Lords during the passage of the health bill.
"Given the government's clear determination to put private profit before patients, we will now seek to overturn this appalling legislation."
During the passage of Andrew Lansley's original Act, Howe promised peers that clinicians "will be under no legal obligation to create new markets".
He added: "This will be made absolutely clear through secondary legislation."
Liberal Democrats are putting pressure behind the scenes for the regulations to be reworded, but it is unclear how any tendering process would escape EU procurement law.