When Tony Blair launched Labour’s 23,000-word manifesto for the May general election, he had high hopes that its 277 policy commitments would provide a legacy that would allow him to leave Downing Street with his modernizing mission accomplished.

As he starts his Christmas break, an exhausted prime minister is wondering whether implementing the manifesto is turning into mission impossible. Labour MPs show little appetite for the reforms, even though they stood on the same manifesto. In many Labour minds, “radical” change has become a bad thing. MPs say they would prefer the brand of reform offered by Gordon Brown.

Blair is also losing his authority in his Cabinet. Pensions was one of the big issues he wanted to resolve before leaving Downing Street. A commission chaired by Lord Turner of Ecchinswell produced a coherent package. Blair judged it a very good piece of work that should form the basis of the government’s strategy. Ministers were consulted, lines to take carefully prepared and agreed. But the Turner report was scuppered by a pre-emptive strike by Gordon Brown who, unlike Blair, does not like the proposed shift away from means-tested help to a more generous basic state pension for all.

Brown pointedly declined to endorse the deal on the European Union budget agreed by Blair at the Brussels summit a week ago. He has not come out against it, but put enough distance between himself and Blair to suggest that he would have done things differently. Precisely how, we don’t know.

Cabinet discipline has also broken down on education — and spectacularly. A lowly Parliamentary Private Secretary at the Department for Education and Skills must resign because he cannot stomach the schools White Paper; others on the bottom rung of the government ladder may also jump. Yet John Prescott rubbishes the proposals in a newspaper interview and Blair is powerless to bring him into line. If there is one person whose support the prime minister needs, it is his deputy’s. His remarks do not signal a withdrawal of that support. But the moment that happens, Blair will have to send for the removal men.

Education provides a good example of how quickly things have moved on since the election. When the manifesto was launched, Blair talked up “radical” proposals on “choice” for parents and freedom for individual schools. In truth, the proposals were never that radical, but his language worried many of his own backbenchers. Now he seeks to reassure them by drawing a dividing line with the Tories, saying he opposes selection by ability. But many don’t trust him and the government’s presentation of the proposals has been poor.

The prime minister will make some changes to the Education Bill to woo “soft” rebels in the hope of securing its passage without relying on the support of the Tory opposition. But he won’t abandon his radical rhetoric or dilute his reforms to the point where they become meaningless. Otherwise, there would be no point in him staying on.

Blair hopes he will still be prime minister next Christmas. But if his party decides it does not want his brand of reforms, he might hang up his gloves sooner than we expect.