The Prime Minister may have won the vote on the education Bill this week, but he had to rely on Tories accompanying him though the "yes" lobby. That means the legislation could face a mauling before becoming law.
A hard core of Labour rebels could not be persuaded by the concessions already made and by last-minute reassurances by Ruth Kelly that the Bill will not undermine comprehensive education. This leaves the Government beholden to the Tories as the Bill progresses.
MPs voted to give the Bill a second reading by 458 votes to 115, with 51 Labour rebels joining Liberal Democrats in the "no" lobby.
They did so despite Tony Blair's insistence that: "This is a Labour Bill and should be supported by Labour MPs."
However, Mr Blair survived a second vote which would have slowed down the passage of the Bill.
Though large, the rebellion over the Bill itself was much smaller than feared earlier this year, when more than 90 Labour MPs were threatening to oppose it.
Helen Jones, Labour MP for Warrington north, who voted against the Government said that the Bill would encourage more fundamentalists and supporters of creationism into education. "Is there any evidence that people who have made a lot of money are good at running schools?" she said.
"Well, there is none - zero."
It is, however, only through offering major concessions with hints of more to come that the Government has managed to get significant numbers of its backbenchers back on board.
Now those offers could come back to haunt ministers who face a difficult tactical dilemma as they prepare for the committee stage of the Bill, when it will be scrutinised by MPs.
They know that ringleaders of the original rebellion such as Angela Eagle, the former Home Office minister and twin sister of Maria Eagle, children's minister, only gave their support this week in the expectation that the Government would meet more of their demands in committee.
But the "clarifications" they want could easily be used by the Tories as an excuse to withdraw their support, leaving Tony Blair at the mercy of at least 50 hard-core Labour rebels, determined to defeat him on the Bill whatever happens.
Nick Gibb, Conservative shadow schools minister, told The TES: "We would be alarmed if further concessions were made during the committee stage. We would have to rethink our position."
Meanwhile, the Conservatives will propose a string of amendments to try to reverse concessions already won by Labour backbenchers.
Banning new community schools, removing the ban on admissions interviews and making the admissions code non-statutory are unlikely to be passed by a committee packed with Government loyalists. But the amendments would force ministers into the embarrassing position of having to argue against proposals they made themselves less than six months ago in the white paper.
Potential Labour rebels will be concentrating on ensuring the Bill is more explicit in enforcing the admissions code, contains more controls over which organisations are allowed to run trust schools and waters down the Education Secretary's proposed veto over new community schools.
The campaign against that veto was boosted this week by a National Foundation for Educational Research study showing that community schools were better than foundation and voluntary-aided schools at achieving the GCSE results predicted for their pupils.
Ms Kelly also confirmed that partially-selective schools as well as fully selective grammar schools would be barred from expanding their intakes "for the first time".