Conservative MPs are organising to oppose changes that Deputy Prime Minister Nick Clegg wants to make to the Government's plans for NHS reforms.
In an email sent to all Tory MPs and obtained by the BBC, Nick de Bois, who has previously said the fundamental principles of the overhaul would not be changed, has set out a series of "red lines" from which he says his fellow Tories should not retreat.
He says critics of the Bill have so far "made their voices the loudest", and calls on his fellow Tories to set out their own red lines - "the principles on which we will not budge", adding: "I am determined that we reclaim the debate over the future of the National Health Service from those who seek to use the Bill as a political tool."
The email appears to contrast heavily with Mr Clegg's plans. Addressing charity representatives in London, Mr Clegg said there would be "no sudden, top-down opening up of all NHS services to any qualified provider". But Mr de Bois's email says "Government should do nothing that stands" in the way of any qualified provider, including private companies and charities, providing care.
Mr de Bois also says there should be a clear date - April 2013 - "when statutory responsibility must transfer from the top-down bureaucracy to GP consortia".
But Mr Clegg said there should be "no arbitrary deadline" for that. He also suggested NHS reforms could be delayed by weeks, if not months - with the Health and Social Care Bill going back to a committee of MPs for further scrutiny.
The Bill passed the Commons committee stage at the end of March after two months of discussion before being stopped in its tracks as part of the Government's "listening exercise".
Mr Clegg said it is vital that the Government gets the Bill right. "I don't think it would be right for us to hold this listening exercise - to make big changes to the legislation - and then to seek to bounce it through Parliament.
"I think it's very important that MPs who are accountable to millions of patients up and down the country really have the opportunity to look at the details of what we are proposing. I think that's why we will need to send the Bill back to committee.
"I have always said that it is best to take our time to get it right rather than move too fast and risk getting the details wrong. We will introduce substantive, big changes. My desire - I think everyone's desire - is just to get it right. The NHS is simply too precious, too important to millions of people in this country to rush things and get it wrong."