If you had not read any political story for the past two weeks, you would wonder why Mr Blair was in such deep trouble. After all, the economy is still pretty strong, despite the slight pick-up in inflation and unemployment. Reforms of public services are starting to work through. True, there are significant foreign policy difficulties in Lebanon, Iraq and Afghanistan, but these do not affect most people.

This is unlike the final days of Margaret Thatcher in the autumn of 1990, when the Government faced a deteriorating economic situation, civil unrest and non-compliance over the poll tax, and deep party divisions over its European policy. And the ruling Tories were much farther behind in the polls than Labour now is.

So, for the moment, the machinery of government carries on. Today, for instance, Mr Blair and Alan Johnson will announce the first wave of trust schools, 27 groups covering 45 schools, with more to come.

Moreover, the Government is advancing rapidly towards its goal of 200 academies, one of which in Barnet (the London Academy) will shortly be opened by David Cameron. At the same time, patient choice and diversity of provision is being extended in the health service. The same story is repeated across Whitehall on pension reform, energy and law and order.

The key to all these reforms is ministerial will and drive. If civil servants detect that a prime minister is losing his authority, they will be less enthusiastic about implementing his policies. One key Blairite minister wondered yesterday how long he had got to push through reforms.

If Mr Blair announces a clear date and timetable, not only will this trigger a continuous leadership election between now and then but the workings of Whitehall could be paralysed well before Mr Blair leaves.

Ambitious ministers and wary civil servants will pay less attention to what Mr Blair wants than to guessing the plans and priorities of the incoming team.

Underlying all this is the simmering debate between Blairites and Brownites over public service reform. As Ed Balls argued last weekend, there are no fundamental ideological differences.

The Brownites say, however, that they do not want their hands to be tied by Blairite attempts to define the future of new Labour and to secure prior commitments from leadership contenders. Mr Brown will, of course, have his own style and views. But what are his allies really saying? Do they agree with the current schools and health reforms? And if not, what are their alternatives? But for all the talk last night from Jacqui Smith, the Chief Whip, about a stable and orderly transition, as likely is a period of uncertainty, drift and loss of direction.

That is why it is not just a matter of Mr Blair saying when he is going, but also of demonstrating that he still has an agenda, and, above all, the power and authority to push it through in his remaining months in office. Both are now in doubt.

Times Recommends

• Times Christmas appeal: Letter from the Editor
• Conferences — what a waste of money
• Schools supremo learns a painful lesson