The Association of Grant-Maintained and Aided Schools voiced serious concerns about the controversial scheme as the Government consultation period closed today.
"We see no real need for this," said John Edwards, its secretary. "We feel there is not a great deal to be said for a fast-track for voluntary-aided schools."
Like both the Roman Catholic and Anglican Churches, the association was unhappy at suggestions that voluntary-aided schools need not ballot parents on opting out.
The association was also upset about the prospect of an end to public consultation about grant-maintained status.
"Objections that are made by appropriate people are valid. They are put forward for consideration as part of the proper democratic process," said Mr Edwards.
The association has now called on ministers to blur the distinctions between GM and VA schools by lowering the amount of money church schools have to raise for capital works and external repairs from 15 per cent to 10 per cent.
It also wants voluntary-aided schools to be given extra money through local management schemes in recognition of the fact that they are teachers' employers.
The cash could be used, for example, to pay a body other than the local authority to run the school's payroll. It could also be spent on legal and employment advice.
Mr Edwards said: "A lot of aided schools find it quite difficult to raise the 15 per cent and we believe it should now be lowered.
"We don't think it should go any lower than (10 per cent) but a drop of that size would ensure schools could manage to raise the money and still retain a stake in the school."
The fast-track proposal was announced by the Prime Minister in a speech to GM heads and governors in September, when he claimed: "Grant-maintained status is the logical choice for church schools."
Ministers expect the proposal will meet serious opposition in the House of Lords, whose members include several influential bishops. The Churches have already dismissed it as discriminatory, divisive, and "a disaster".
Local Schools Information, the local authority-backed advisory body, said that if the 4,000 voluntary-aided schools converted to GM status the annual cost would be Pounds 165 million.
It added: "The potential for throwing the whole school system into turmoil is glaringly obvious: divisions would be caused among parents, governors, staff and heads; church and other schools; VA, voluntary controlled and county schools.
"This would be a major distraction from the pressing task of focusing attention on the need to raise levels of aspiration and achievement in schools; a task on which there are promising signs of progress - but a task which requires those involved to work harmoniously together."