Tony Blair is expected to announce he is standing down as Labour leader today after a decade in Downing Street, paving the way for Gordon Brown to succeed him as British Prime Minister.
Mr Blair will first tell Cabinet colleagues of his intentions at their regular 9am Thursday meeting at No 10, then travel to his Sedgefield, Co Durham, constituency to make a public pronouncement.
Weeks of speculation over the timing were ended by the PM's official spokesman, who told reporters: "There will be a Cabinet at nine o'clock. I don't think that will be quite as long as usual.
"The Prime Minister will then go elsewhere to make an announcement and that will be all that happens. There will be nothing said in Downing Street."
Mr Blair remains as Labour leader until his successor is formally elected at a special party conference, and as Prime Minister until he hands in his seals of office to the Queen.
Labour's National Executive Committee will meet within 72 hours of the confirmation to agree the exact timetable for an election to replace both Mr Blair and his deputy John Prescott.
The whole election process will take about seven weeks, meaning Mr Brown - if he is elected - will take office some time in late June or early July.
Mr Prescott announced at Labour's annual conference last September that he would quit at the same time as the Prime Minister. A report in The Sun newspaper suggests Mr Prescott will delay his own announcement until Sunday.
It was confirmed that former Labour MP Chris Leslie will run the logistical side of the Brown campaign, working under Commons leader Jack Straw.
The Chancellor is likely to face only a token left-wing challenge from either backbencher John McDonnell or former minister Michael Meacher. The two will announce which of them is to try to stand against the Chancellor.