His private assurances back up the public pledge Labour MPs forced out of him last Monday, that he would give "ample time" to his successor to prepare to fight the next election. In the past, Mr Blair has insisted he would serve a "full term", and allies have suggested he would go in 2008 at the earliest.
But after a torrid month in which his Government has been rocked by a series of scandals and was roundly defeated at the polls, Mr Blair has been forced to tell his senior colleagues he will go next year. The end of next summer's parliamentary term, almost certain to be before 31 July, is seen by Gordon Brown's camp as the ideal moment to hand over to his successor.
One cabinet minister, asked if he had been told by Mr Blair that he was going next summer, said: "I'm not going to tell you exactly what Tony said but I wouldn't disagree with that." The minister is not considered to be an ally of Mr Brown.
Another minister said "almost half the Cabinet" had now been given private assurances about a departure date by Mr Blair.
But the Prime Minister told senior colleagues he would continue to refuse to confirm the arrangement in public because he fears the Tories would "mount a countdown clock in Westminster". He hopes to leave vague the exact date while admitting it will be between next May's local, Scottish and Welsh elections and the autumn party conference.
Mr Brown's camp wants Mr Blair to remain in No 10 until the succession is settled to avoid the need for any caretaker prime minister. More detailed discussions between the pair must now settle the question of when and in what terms Mr Blair announces his departure, say the Chancellor's supporters.
Suggestions that Lord Kinnock could replace the discredited John Prescott as an honest broker in those discussions received a cautious welcome yesterday.
"What we are seeing are senior figures wanting to become involved, wanting to know what's going on so they can reassure others," said a senior member of the Brown camp.
Lord Soley, a former chairman of the Parliamentary Labour Party, is another possible broker-cum-witness to the details of the handover deal.
Running a leadership contest would be a matter for Labour's National Executive Committee, and it, too, may soon become involved in the succession talks.
Mr Prescott's position remains tenuous, according to his cabinet colleagues. The Deputy Prime Minister has failed to answer satisfactorily why he deserves his pay and perks now he has been stripped of his department. He also remains at the mercy of further revelations about his private life. Most believe his "referee" role is now a polite fiction maintained only because it is mutually convenient for Mr Blair and Mr Brown.
Neither wants a race for the deputy leadership of the Labour Party that Mr Prescott's resignation could trigger.Reuse content