The Conservatives are ruling out a widespread extension of academic selection in England, saying there will be no new grammars.
David Willetts is set to outline Conservative policy
But they want specialist schools rules simplified so 10% of pupils can be selected on aptitude for any subject.
Leader David Cameron and education spokesman David Willetts are outlining their policy towards schools on Monday.
They are expected to say that good schools should be able to expand by forming federations with other schools.
A problem facing the party is that policies proposed by the government have overtaken its ideas - such as on improving school meals, teaching reading through synthetic phonics and tightening up on discipline.
The idea of "expansion by federation" sounds rather like the government's own proposed "trust schools".
These state schools with more autonomy were put forward in a White Paper this autumn which has proved highly contentious with many Labour MPs, including the Deputy Prime Minister, John Prescott.
One of their fears - despite ministers' assurances that it cannot happen - is of an increase in academic selection for secondary school places.
At present, certain categories of specialist school - which most secondary schools in England now are - can select 10% of their pupils by "aptitude" for their specialist subject.
These are music, sports, performing arts, languages and technology schools existing before November 2004.
The others cannot: newer technology schools, maths, science, engineering, business and enterprise, humanities.
The Tories feel this is "an extraordinary anomaly".
Mr Willetts said: "I would think it will be simple and straightforward to say, if a school has a specialist subject, they should be able to select 10% on that."
On Sunday, Labour leader Tony Blair repeated the charge that the Tories would reintroduce the 11-plus.
But Mr Willetts said it was not a return to 11-plus testing. It was about taking seriously "some of Tony Blair's own rhetoric".
"The real question where we can work with him is how we can enable good schools to expand."
Schools Minister Jacqui Smith said on Today that the Commons education select committee and the schools adjudicator - who rules on admissions disputes - had said that selection by "aptitude" and "ability" were essentially the same.
"It doesn't make sense to be selecting out a few on the basis of what amounts to academic ability," she said.
Mr Willetts also signalled the possible end of the "pupil passport" idea from the last election.
This would have allowed parents state funding to send their child to any school, including those in the independent sector providing they did not charge more than the equivalent state school place cost.
"That was something we had last time and we are no longer committed to that," he said.
Instead he wanted to see how good schools outside the state system, catering for parents who felt they had been let down, could acquire state funding.