The conference went on to condemn overwhelmingly the Government's proposals to give parents vouchers worth pounds 1,100 to redeem for nursery education from the public, private or voluntary sectors.
Don Foster, Liberal Democrat education spokesman, dubbed Gillian Shephard, Secretary of State for Education, "Little Miss Helpful", but said: "It's no use if you can't deliver. And her gimmick of nursery vouchers helps nobody.
"Vouchers will not deliver provision where none exists ... will not ensure high quality, and will do nothing to boost provision for three-year-olds."
The conference vote commits the party to providing "quality" early-years education for all three- and four-year-olds whose parents want it, within the lifetime of a parliament. Neither the Government nor Labour have set time-limits for the implementation of their pledges.
The Liberal Democrats are committed to a 1p in the pound income-tax increase if that is needed to pay for pounds 2bn worth of improvements in education.
The promise to give early years education first claim on the money could cost between pounds 600m and pounds 900m a year.
Even Conservative councils have severe reservations about the financial impact of the Government's voucher plans. But while the conference backed an amendment condemning the scheme as "totally inadequate" and a "cash- for-votes" bribe, the party has not closed the door to the idea of vouchers.
Sarah Ludford, a member of the federal policy committee and a London Borough of Islington councillor, said that the right was being allowed to hijack a liberal idea. "We want to dispense power to people to make their own decisions and choices," she said.
Patrick Short, from Kensington and Chelsea, said the amendment did not mean that the party was opposed to any voucher scheme. "There might be one I can agree with." Paddy Ashdown, the Liberal Democrat leader, is also believed not to have ruled out the idea of vouchers.
The party backed the establishment of minimum criteria for care, the curriculum, premises and staffing of nursery schools while giving a guarantee that they would have appropriately qualified staff and be led by a graduate.