The Government must allow for-profit companies to run free schools if it wants to avoid them becoming "statistically minor", the chair of the influential Commons education select committee has said.
Graham Stuart, a Conservative, has dismissed the chances of free schools having a significant impact unless Michael Gove embraces profit-making businesses as the key to making the policy a success.
In an interview with The TES, Mr Stuart said: "Free schools, especially without allowing profit- making companies to come in and do it and thus raise capital, will remain statistically minor in the overall scheme of things.
"It seems to suit both Left and Right to make free schools a big issue so they can have an ideological bun-fight, but I'm not sure that they will be that significant overall."
Mr Stuart is the latest in a line of high-profile decision-makers to call for profit-making companies to be allowed to take control of running parent and teacher-led independent state schools.
In 2009, Anders Hultin, architect of Sweden's free school programme and now Pearson's managing director of school improvement, said the Conservatives' free school policy "could fail" unless the party allowed profit-making providers to make money from the venture.
Mr Stuart's comments have won some support from those setting up non profit-making schools under the existing framework.
Author Toby Young, who is setting up the West London Free School, said: "If it had been possible to bring in an experienced provider at the beginning of the process, that would have made our lives much easier.
"But having come this far without one, there doesn't seem much point in getting into bed with one now. We've managed to recruit plenty of experienced teachers to our steering committee.
"If the Department for Education wants to roll out free schools on a grand scale, in the long run it needs to change the rules so for-profit providers are allowed to set up, own and operate taxpayer-funded schools.
"However, that would mean opening up another front in the education war and I think it's unlikely to happen in the life of this Parliament."
ATL general secretary Mary Bousted described Mr Stuart's comments as the "thin end of the wedge", voicing concerns that the Government could be prepared to give the green light to for-profit companies.
She said: "These free schools are just a Trojan horse for charging for profit. If you look at the New Schools Network website, it is full of companies advertising to supply anything for a profit.
"The problem is money that should be spent on education ends up lining the pockets of shareholders. Graham Stuart is quite right; unless free schools can be run for profit, there will be very few of them. The only way they can become cost-effective is if they are run at a profit."
A Department for Education spokesman said: "There are no plans to allow free schools to make profit. As with academies, any income earned by the charitable trust must be reinvested to improve and advance education for pupils.
"As is currently the case with existing schools, governing bodies are allowed to sub-contract elements of the management of the school to other organisations - including private companies."