Education Secretary Ruth Kelly has defended the government's plans to shake up schools in England.
She has insisted the reforms will not mean a return to widespread selection by ability, as some Labour MPs fear.
Ms Kelly presented the plans to the Cabinet and later to new head teachers, saying they were essential and "rooted in Labour values".
The government is facing backbench opposition to the plans, which some MPs say reflect old Tory policies.
Under the plans, schools would gain more independence from local authorities and could become "trust schools" with more control over their finances, staff and admissions (which pupils they take).
The education secretary told head teachers it was a myth that the changes would bring back selection by pupils' ability.
"At the heart of this vision are self governing trust schools that will be able to employ their own staff and control their own assets," she said.
"They'll also be able to apply for additional flexibilities if they feel that that would enable them to offer better services to local people. And they'll be able to set their own admissions arrangements.
"But let me be crystal clear. These arrangements will be within the admissions code that ensure fair admissions. There will be no free for all. And there will be no return to selection by ability by the front door, back door, trap door, green door or any other door at all."
However, she acknowledged that the government needed to do more to spell out its vision.
"I am clear that we have to explain better and listen more to the profession and parents as well as with my own party," she said.
"Fundamentally this White Paper is about raising standards for all pupils. Especially those in the most deprived areas and from the most disadvantaged backgrounds. It is not, as some fear, just the middle classes."
The proposals are due to form the basis of an Education Bill early in the New Year, but some senior Labour MPs have voiced concerns.
The concerns focus on four areas:
- trust schools will create a hierarchy in education
- their greater autonomy will create an admissions free-for-all
- the middle classes will benefit most from new powers for parents
- elected local education authorities will lose their powers
Ruth Kelly has rejected comparisons with Tory grant-maintained schools, which were scrapped when Labour returned to power.
She said trust schools would be given greater freedoms but would be expected to collaborate - not compete - with neighbouring schools.
Although no watering down of the plans is likely, the government appears to have been taken aback by the level of opposition to them and recognises it has a lot of persuading to do.
BBC political correspondent James Hardy said many Labour MPs would not accept the government's reassurances.
"There are an awful lot of backbenchers who are very upset about these proposals," he said.
"There was a rebellion of 49 on the anti-terrorism measures last week. It is estimated up to another 50 could be prepared to join a revolt over the Education Bill. That could deliver a crushing defeat to Tony Blair."
A Downing Street spokesman said Ms Kelly's presentation to the Cabinet had received "strong and enthusiastic" support.
It had also been unanimous and "in time" all members of the Cabinet would make the case publicly for the reforms, he said.