The American President and his wife, Hillary, will arrive in Downing Street today for an extended visit that could provide the kind of working relationship that Harold Macmillan established with President John Kennedy, and Margaret Thatcher with President Ronald Reagan.
During the day-long visit, the President will address a meeting of the Cabinet, as President Richard Nixon did in 1969, and Cherie Booth and Mrs Clinton will spend the day together. They have not met before, but they have a legal career in common.
While Downing Street was being coy about the details of the "social" programme, a visit to a London landmark like the new Globe Theatre is possible.
But the meat of the day will come in one-to-one talks between the two leaders, who share a keen interest in education, job creation programmes, and welfare reform.
The influence of the President on Northern Ireland could be more immediate and dramatic, if he is persuaded to use all his covert power and influence to persuade Sinn Fein and the IRA that they must resume their ceasefire and open the way for top-levels talks on the future of Ireland.
Mr Blair will repeat during the day that if there is a genuine ceasefire, there will be "no unnecessary delay" in admitting Sinn Fein to multi-party talks. Other issues that are expected to be covered include Nato, Bosnia, Hong Kong and the agenda for the forthcoming leading industrial nations summit in Denver.
On Europe, the Prime Minister's office said last night that Mr Blair had never believed Britain had to choose between the special relationship with the United States or Europe. The President wanted Britain strong in Europe and that was the way to ensure the special relationship with the US worked to mutual advantage.
The Prime Minister's office said Mr Blair wanted to exploit his domestic election success in the diplomatic front. "He is well aware that the honeymoon won't last forever," a spokesman said, "but that while it does, he intends to use it for Britain's advantage and to stamp Britain on the world map."
After a morning of talks, followed by lunch with officials on both sides, the two men are expected to stage a press conference in the garden of 10 Downing Street before turning to a more relaxed itinerary. The President and Mrs Clinton are expected to leave London sometime in the evening, to return to the United States.
The pace of political activity noticeably quickened in Northern Ireland yesterday as the Government and others worked towards a new IRA ceasefire, a peaceful marching season and progress in multi-party talks, writes David McKittrick.
The Secretary of State for Northern Ireland, Mo Mowlam, concentrated on the controversial parades issue, meeting leaders of two of the main Protestant marching organisations, the Orange Order and Apprentice Boys of Derry.
Ms Mowlam, who later described the contacts as useful, has already met representatives of Catholic residents' groups, many of whom object to loyalist marches through their areas. The authorities are anxious to avoid another damaging summer of marching confrontations.
At the same time, Northern Ireland Office officials held their second meeting with a Sinn Fein delegation led by Martin McGuinness, who said republicans were "absolutely committed and dedicated to moving their entire situation forward". The meeting, at Stormont Castle, lasted for three- and-a-half hours, ending with agreement that a third session of talks should be held.Reuse content