In becoming the first Cabinet minister to propose specific spending cuts, the Prime Minister's staunchest ally, Ed Balls, has shown his loyalty one more time. In interviews yesterday, he volunteered that education spending could be cut by £2bn by dint of pay restraint and slimming the ranks of senior staff. Thus has the Children's Secretary put his oar into the escalating contest for public spending cuts and tried to outmanoeuvre the Conservatives. As was heard loud and clear also from the Liberal Democrats in Bournemouth yesterday, the debate in this conference season is now unambiguously about who can cut most from public spending.

There are two difficulties with Mr Balls's approach, however, both for himself and for Gordon Brown. The more specific are the cuts that ministers propose, the more hostages to fortune they offer up. The Government may believe it can shame the Conservatives into responding with equally detailed bids, which can then be used to trap them, but there is no guarantee that such competitive cutting will work with David Cameron's ever more well-oiled party machine.

The other difficulty is that any proposed cuts will provoke opposition from who stand to lose, especially if the costings are as fuzzy as these appear to be. In appearing to target senior teachers and pay, Mr Balls is on particularly shaky ground. No one has done more to encourage financial and managerial autonomy of schools than this government – while requiring rigid adherence to all finer points of the national curriculum. Head teachers have been encouraged to become quasi-executives. The message now being sent is that they are "bureaucrats" and as such dispensable, or at least ripe for pruning.

There surely are economies to be made in the education budget, but we suspect Mr Balls might find more fat closer to home. As schools enjoy more autonomy, his department's role should be shrinking, but seems not to be, while a quango cull in education is overdue. It is not good politics either to alienate the big schools lobby just before an election, but that is a whole other topic.