Tony Blair’s interview with The Times today marks the end of the holidays and the return of the political season. In it, he both defies those who want him to set out a departure for his resignation and implies that such a formal proposal is unnecessary. With a slightly injured tone he asserts that he is being “reasonable” and that it is others who are stoking speculation about him. He will not, he insists, attempt to go “on and on” as Margaret Thatcher did and will leave “ample time” for his successor to settle in before he has to win the backing of voters. His critics, it is strongly hinted, should pipe down and let him get on with his business.

Which, of course, they will not, and Mr Blair is well aware of it. If this is really the Prime Minister’s last word on the subject before the Labour Party conference in Manchester, then there is every chance that his fate, not the merits of city academies or reform of the NHS, will be the principal subject on the agenda. A prime minister has immense authority but the power to prohibit a discussion is not part of it. The idea that the direction of the Government can be disentangled from the leadership question is utterly illusory.

That, too, Mr Blair must appreciate. His words should, therefore, be seen more as a holding strategy than Holy Writ set in stone and beyond amendment. The Prime Minister and those who would have him out far sooner rather than later are engaged in a game of political poker in which bluff is an even larger element than usual. It is not in Mr Blair’s interests to concede anything more than he has to at this stage in proceedings. If he offered a hint that he has a departure date in mind, he has concluded, he would lose control over his future altogether.

As a position for the here and now, this is understandable. British politics is in uncharted territory. There is no precise precedent for a Prime Minister pre-announcing his resignation and neither he, his inner circle, Gordon Brown, his most intransigent internal opponents or the confused collection of Labour MPs who comprise the muddle in the middle know how best to handle the situation. As the constitutional procedure for forcibly unseating an incumbent Labour prime minister is complex and unenticing, Mr Blair may calculate that others will have to fold if he sits determined at the table.

The Prime Minister would, nevertheless, be sorely mistaken if he assumed that he has all the cards. The character of his tenure has changed fundamentally. He cannot plan for the succession based on his personal preferences and those of his most passionate supporters alone. He requires not simply the acquiescence but also the assent of Mr Brown and other Cabinet figures. If his private signals toward them are no more illuminating than what he opts to have produced in print, then he will risk mutiny at an awkward moment. If that comes, as Mrs Thatcher found to her cost, it can be swift and brutal.

The only way in which Labour’s conversation over the next few months will be about anything other than the leadership question is if Mr Blair can ensure that it is just those who can be dismissed as “the usual suspects” that talk about it. He cannot expect Delphic hints, nods and winks or a vague pledge about providing “ample time” to be enough for his closest colleagues.

The Prime Minister says, rightly, of his party that “new Labour or bust” is the choice that lies before it. In in his case, though, it is “consensus or bust” that will decide how he leaves office.