Alison King, chair of the Local Government Association's new children and young people board, told The TES: "If schools are floated almost totally free of education authorities it will be very difficult to drive forward our improvement agenda for children's services."
The leader of Norfolk county council said she was very concerned about the Government's five-year plan to give LEAs less control over funding and to reduce their admissions role by making it easier for schools to achieve foundation status.
She said that Conservative proposals to give LEAs even less of a role, by making every school grant-maintained and creating a national funding agency, caused her the "same sort of difficulties".
"I am quite free to say to my party that I am not happy about something it is suggesting," she said. "When you get these sort of proposals the devil is in the detail. Politicians can think things up which don't translate terribly well into practice."
A former social worker, Mrs King - who describes herself as being on the left of her party - was chair of the LGA's social affairs and health executive.
The decision to streamline the LGA was taken following the June elections when the Conservatives took control of the lobbying organisation for the first time. From next month its existing 19 executives will be replaced by six boards.
Mrs King's appointment marks the end of Graham Lane's seven-year stint as chair of the LGA's education executive. The Labour leader of east London's Newham council has also lost his post as chair of NEOST, the teachers' employers body, after eight years.
The other 13 members of the LGA children and young people board have yet to be decided.