The government fought off a backbench rebellion of 69 MPs last night when the Conservatives helped them get through the report stage of the education bill.
The Labour rebels broke the party line to support an amendment forcing schools who hoped to become self-governing trusts to first gain approval of parents through a ballot.
However, the Conservatives backed the government and the amendment was comfortably beaten by 412 votes to 121 - the second time they have saved the controversial bill, after they helped it through its second reading in March.
Further votes are due later today when MPs return to debate the final stages of the legislation, which aims to create a network of self-governing trust schools with control over their own assets, staff and admissions.
During last night's debate, education secretary Alan Johnson rejected the ballot proposals as "unnecessarily bureaucratic" and insisted the obligation on schools to consult parents was enough to ensure their views were taken into account.
"What we say is that to insist in legislation that on every occasion.the only method of consultation must be a ballot is too dictatorial and unneccessarily prescriptive," he said.
But Labour MP John Grogan rejected this argument, saying he was surprised to hear former union leader Mr Johnson dismiss the "one member one vote" system in this way, adding: "I must urge those on my front bench to resist the forces of conservatism."
Mr Johnson insisted schools would have the freedom to hold a ballot if they wished, but Labour MP David Chaytor noted that this variation was a "recipe for chaos and would lead to challenges".
The Conservatives backed the government, however, with education spokesman Nick Gibb insisting ballots would not be used to give power to parents, but instead used for political ends by those who objected to the whole idea of trust schools.
Senior Tory MP Edward Leigh noted that the ballot system had been introduced in his party's plans for grant-maintained schools in the past, and admitted it was a "huge error".
"Those who were opposed to grant-maintained schools on any basis whipped up sentiment against them, but parents could be persuaded because they are conservative and do not want change," he insisted.
The support of the Conservatives meant the amendment was defeated, but the rebellion will be seen as a sign of the weakening authority of Tony Blair.
John MacDonnell, Labour MP and chairman of the socialist campaign group, warned last night: "This is a crippling blow to the education bill, which the prime minister is only able to force through on the back of Tory votes. New Labour is in free-fall."
Also last night, a Conservative amendment to give local authorities and the secretary of state a new duty to encourage schools to become self-governing trusts - something the party insisted was needed to increase diversity - was rejected by 376 to 169.