Such a charge would infuriate ministers, but leave the Tories highly vulnerable. Labour has been accusing the Government of planning the privatisation of the NHS for some time, but the backing of the doctors would make the charge stick.
Ministerial sources said they would be seeking a compromise by offering movement on other issues, including a BMA demand for a proper timetable for pilot schemes in primary care, before they are introduced nationally. But the government sources appeared to rule out any retreat on the proposals to allow private companies to hire GPs.
The plan is part of the NHS Primary Care Bill, which is due to go through its final stages in the Lords tomorrow before starting its passage through the Commons on 11 February. If there is an early election, there is a strong chance that Mr Dorrell will be forced to concede to Labour to get the rest of the Bill on the Statute Book.