MP Julia Drown was defying Tony Blair today by voting against plans to create "super-hospitals" with new financial powers.
The Labour MP for South Swin-don fears that setting up foundation hospitals would hand too much power to hospital managers at the expense of other aspects of health care.
Ms Drown pledged to vote for a rebel amendment to kill the Health and Social Care Bill when it was debated in the House of Commons today.
The Bill will set up the first wave of around 12 foundation hospitals, with freedom to set their own pay levels and recruit staff from elsewhere.
Opponents of the scheme fear they will attract the best staff by offering better salaries and will be given extra cash at the expense of less well-performing trusts.
Swindon and Marlborough NHS Trust will not be among the first wave, because it failed to achieve a three star rating in the hospital league tables which were published last year.
Ms Drown said: "Giving hospitals foundation status will move the focus away from reducing waiting times and improving the quality of clinical care."
A former NHS accountant, Ms Drown is a member of the Commons health select committee, which has produced a report - published today criticising the plans.
More than 120 Labour MPs have signed a Commons motion opposing foundation hospitals threatening the government with defeat tonight.
Swindon North MP Michael Wills, the Parliamentary Under Secretary for the Criminal Justice System, is expected to back the bill.
However, he was not available for comment.
Swindon's Great Western Hospital hospital spokesman, Chris Birdsall, said: "As a trust we are performing well, but we are not eligible to apply for foundation status at the moment.
"As to the rights and wrongs of the new system, that is a matter for the politicians. Our priority is to provide the very best service for our patients."
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