Labour's pledge to abolish the Assisted Places Scheme will mean the loss of Pounds 110 million fee income to the 360 schools that participate. The impact is likely to be greatest at schools such as Wisbech in Cambridgeshire, where more than half the pupils have at least part of their fees met by the scheme.
In advance of the election, a handful of mainly Catholic schools have taken steps to join the state sector. St Anselm's College in the Wirral has become grant-maintained and St Joseph's College in Stoke-on-Trent is due to join the state sector in April. Two others are in process - St Ambrose in Trafford and St Edward's in Liverpool.
The Independent Schools Information Service does not expect more than a few schools to take the grant-maintained route, however, partly because the future of the GM sector is uncertain under Labour.
According to Dick Davison, ISIS deputy director, schools are examining a range of options. He said: "The schools in the scheme are mainly academically selective institutions in urban areas, and I am confident there will not be any that face closure. It may be that some will reduce their intake and others may lower their admission hurdles.
"The most regrettable aspect of any plan to abolish the scheme is that its demise will inevitably lead to the independent sector becoming more socially exclusive," he said.
At Wisbech, where 340 of the 635 pupils are on the Assisted Places Scheme, the school may contract. Bob Repper, the head, is confident it could survive the loss of more than Pounds 1 million in income.
"Our roll used to be 400 and we were encouraged to expand because there is a shortage of places. If necessary we could go back to the original numbers, " he said.
The school, he insists, has local support across all parties. He cites the fact that Virginia Bucknor, the Labour candidate for the constituency, NE Cambridgeshire, sent her son to the school.
"We have had meetings with Peter Kilfoyle (one of Labour's education team) and he understands that in this area there is a need for the school," he says.
Wolverhampton grammar, where 295 of 760 pupils are on assisted places, is looking at the possibility of using trust funds to offer bursaries.
The head, Bernard Trafford, believes abolition of the scheme could be felt by less popular schools as more places become available in institutions that formerly took assisted places.
"In the end, I don't think we will change very much, except that we will become a lot more exclusive. It may be that other independents will go to the wall," he said.
Similar strategies are being considered at Manchester Grammar, the largest independent school. It has 290 assisted places out of 1,450. Dr Mark Stephen, High Master, said the school is considering a financial plan to increase finance from letting buildings and the prospects for increasing capital funds that could be used for bursaries.
"We are not prepared to lower the standard of entry and we don't believe we will have to," he said.