Tony Blair has ruled out big changes to his education reform plans despite a challenge by more than 50 Labour MPs.
The education reforms are proving controversial
He told MPs he would not delay the introduction of trust schools, with more say over admissions and finances, in England or adopt other changes.
Tory leader David Cameron said Mr Blair faced a choice between his education White Paper and "the white flag".
Mr Blair countered, during prime minister's questions, that Mr Cameron wanted a return to academic selection.
The exchanges came as five ex-ministers and other Labour MPs unveiled alternative plans to Mr Blair's education reforms.
They are calling for local authorities to get extra powers to coordinate school admissions.
SCHOOLS WHITE PAPER
Allowing schools to become independent trusts, with more say over admissions, staffing and finances
Local authorities become "champions" for good schools, rather than education providers
Parents encouraged to set up their own schools
A "schools commissioner" and network of advisers to help parents
More help with transport costs for poorer families
The idea of allowing schools to become independent trusts - with more control over their own finances, staffing and admissions - must be "more fully developed" before they are approved by Parliament, the MPs add.
Ex-education secretary Lady Morris has threatened to vote against party policy for the first time over the issue.
Ministers insist the plans do not mean a return to selection by ability and that they will improve standards.
Challenged by Mr Cameron to say whether he would be accepting the rebel amendments, Mr Blair replied: "We will stick with the changes in the White Paper because they are the right changes to make."
Councils get power to "refuse or restrain" setting up or expansion of schools where it might damage other schools
Local authorities to "coordinate" admissions for all schools
Idea of trust schools to be tested more thoroughly before passing into law
No need to establish commissioner, which duplicates role of local authorities
He conceded there were "differences" with some Labour critics of the plan, who were unveiling their alternative proposals on Wednesday.
But he insisted that he also had differences with Mr Cameron because the new Tory leader supported "bringing back academic selection".
Mr Cameron said Mr Blair had a choice: "With our support, you can have the reforms that our schools need, or you can give in to the Labour Party. Which is it to be - White Paper or white flag?"
Organisers of the alternative Labour MPs' plans, entitled Shaping the Education Bill - Reaching for Consensus, say they have the backing of more than 50 Labour MPs.
Former ministers John Denham, Nick Raynsford, Alan Whitehead, and Angela Eagle are among them.
Mr Denham said he feared the government's reforms would destabilise the system, leaving behind pupils from disadvantaged backgrounds and those in underperforming schools.
He insisted that he and his colleagues were not the "usual suspects" who rebelled against the government. "We are people who have always seen the need to change," he told BBC Radio 4's The World at One.
But that change had to involve reforms "that work", he added.
Labour backbencher Graham Allen said the group's document aimed to make the government plans "more practical and realisable".
"We are hopeful that since this is not an anti-government and negative response, that it will find support throughout Parliament and be a sensible way forward which continues public sector reform while not damaging the prospects of children in under-attaining constituencies like my own."
Education Secretary Ruth Kelly has said the changes will give schools the extra flexibility to offer better services.
"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," she said.
Liberal Democrat education spokesman Ed Davey said: "Parents across the country should be alarmed that Tony Blair is prepared to use Tory support to drive through reforms that will make admissions to schools even more complicated and less fair."