The liberal Democrats have launched a searing attack on Tory plans to reform the curriculum, branding it "confused, ill thought out and naive".
Education spokesman David Laws made the criticism after a recent Commons bill scrutiny committee, claiming he had identified "deep flaws" in the party's policy.
The Conservatives want to reform the national curriculum, and chief among the changes will be a demand for a more detailed knowledge of British history.
But the Tories also plan to expand drastically the number of academies, allowing schools to opt out of teaching the national curriculum.
During the committee, Mr Laws said academies were at the "forefront" of schools dropping core subjects. He added that if a market town was served by a single academy, it could be that those pupils would leave school without the core skills the Tories have repeatedly called for.
Mr Laws said: "The Tory position on the core curriculum is totally incoherent. On the one hand they are saying that all pupils should be learning British history, but then they propose to establish new schools in which there would be no requirement to have a basic knowledge of anything."
He added: "The Conservatives' proposals are confused, ill thought out and naive."
Tory shadow schools minister Nick Gibb said he believed most parents would choose to send their children to schools that provided "rigorous academic education".
If a school was not delivering the education expected by parents, a new provider would be brought in, Mr Gibb added, although a new school could take five or six years to establish. He said: "It will be easier for new providers to come in, and they will begin to provide the education demanded by parents...
"At the moment, we have a system that is letting down significant segments of our population, and I believe that this is the only way in which we can tackle underperforming schools in the long run."
A Conservative spokesman later stated that the national curriculum had "serious flaws".
The party is expected to allow academies immediate exemption from the national curriculum if it wins the election. Following this, the Conservatives will allow all state schools to offer the international GCSE in core subjects from September 2010, if they wish.
The spokesman said: "The curriculum will then be reformed over our first year. This must be based upon global evidence concerning what knowledge can be introduced to children at different ages; it must be a floor, not a ceiling that limits schools' aspiration to introduce children to very challenging ideas at a young age.
He added: "Once reformed, we will stop the constant political interference in the curriculum that has devalued standards; it will not be rewritten every year."