The coalition government has no "plan B" for its controversial proposals to reform the NHS, the House of Lords has heard.
Health secretary Andrew Lansley has seen his Health and Social Care Bill come under heavy fire, with calls for it to be dropped gaining momentum.
The bill, which centres around the responsiblity for the commissioning of health services passing from primary care trusts to GP consortia, is viewed by critics as privatisation of the NHS.
Parliamentary undersecretary of state for health Earl Howe told lords that the government was set on its bill as it was "the right thing to do".
As the bill, which has already racked up 137 amendments, faced the Lords for a second time, Howe was asked by critics if the coalition had a "plan B" considering the level of antagonism against the reforms. He said no.
Former SDP member Lord Owen led the charge against the "massive changes to the architecture of the NHS" but questioned whether it could be stopped now because "so much has already been done".
He quoted an un-named Conservative MP who said: "We are absolutely terrified about the chaos that will happen if the bill is dropped now. Restructuring is a nightmare - un-restructuring would be even worse."
Owen continued: "This raises big questions and is a matter of great concern to this house. It's important that we maintain the position that legislation doesn't have full authority until it's gone through the full process [of both houses]," he added.
Howe assured the house that any restructuring that has taken place was done so under the powers granted to the government by current legislation.
"[The restucturing] is not a permanent solution however, hence we need primary legislation," he said.
The coalition is struggling to maintain momentum with the bill, with the British Medical Association, readers of the British Medical Journal, the Royal College of Nurses and GPs all calling for it to be scrapped.
Lord Owen, who left the Labour Party in the 80s to help form the rebel Social Democratic Party, was revealed in January to have been encouraging Labour to campaign on the NHS reforms.
The last time the bill went through the Lords, he urged fellow members to "cherish the fact that the NHS is one of the most popular institutions in our country".