Tony Blair has warned Labour MPs that they could allow the Conservatives back into power if they defeat his Education Bill in a critical Commons vote next week.
In private meetings with potential Labour rebels, the Prime Minister is comparing the vote on his school reforms a week today with mistakes Labour has made in the past that convinced the voters the party was not fit for power.
They include the Wilson Government's retreat from plans to reform the trade unions in its 1969 White Paper In Place of Strife and Labour's opposition to Margaret Thatcher's proposals to allow council tenants to buy their homes.
With between 60 and 80 Labour MPs threatening to vote against the Education Bill, Mr Blair is ready to rely on the support of the Opposition to ensure the measure secures a second reading next week.
However, a close ally of Mr Blair said yesterday: "What matters most is not the vote but that the Bill is passed into law. The vote is not the defining issue. It is the reforms that are the defining issue."
Mr Blair fears that, if Labour fudges the issue of schools reform, the Tories would be able to campaign at the next election on a pledge to implement the changes he wanted but his party blocked. The Blair ally said: "People will ... go Tory unless we get these reforms through. It is a simple proposition."
Mr Blair is unmoved by criticism from his own side for relying on the Opposition, saying privately that he will not give the rebels "the keys to the kingdom" so he would win the vote without Tory support.
Some Labour critics may be won round by further concessions. They are demanding more safeguards over the financial and ethical standing of the private firms who would be allowed to sponsor trust schools and curbs on the Education Secretary's power to stop local authorities opening comprehensive schools.
However, with many rebels standing their ground, Mr Blair is relying on a tribal appeal for loyalty and warning of grave electoral consequences for Labour if it does not pursue his reform agenda.
Writing in the Labour modernisers' journal Progress, the Prime Minister said: "If we continue to drive our school reforms from the perspective of parents, we will prosper. Put political dogma first, and we will lose.
"The education debate symbolises the future for Labour. Have the courage to reform and empower and we earn the right to stay in office for another generation, setting the political agenda on centre-left values. Avoid reform and duck the challenges and we will not only lose power, we will not deserve it."
Mr Blair said he understood the concerns about the school proposals but insisted many of them were worries about the system as it stood today - varying provision, back-door selection, the way the poorest were not educated well enough. "I agree with these concerns but believe that is why we need to go further. Our proposals are intended to address them," he said.
The Prime Minister said the education reforms were vital in showing the path by which Labour could sustain and renew itself in office. "We have to be the ones taking the hard decisions, meeting the challenges, explaining why change is the only way to make the nation stronger, fairer and better," he said.