Chancellor Gordon Brown is scheduled to take over as Britain's next prime minister when Tony Blair drives to the Buckingham Palace mid-afternoon Wednesday and tenders his resignation.
For the last time, Blair will figure in Prime Minister's Question Time in the House of Commons.
Later he is expected to proceed to the Sedgefield constituency in north England to announce his resignation as a member of parliament too.
The announcement of Blair taking over as the next Middle East envoy is expected to be made on Wednesday. Talks to outline his mandate in the new job were held in Jerusalem between leaders of the European Union, Russia, the UN and the US.
After taking over as the 52nd prime minister of Britain, Brown will address the nation as the prime minister.
Meanwhile, US President George W Bush paid tributes to Blair and told The Sun that was he "very talented" and rejected claims the outgoing prime minister was his poodle as "silly ridicule".
The president told the Sun: "Tony's had a great run and history will judge him kindly. He's a very talented man for whom I've got a great deal of respect. I've heard he's been called Bush's poodle. He's bigger than that.
"We are working together to achieve global peace in the face of enormous danger. This kind of thing is just silly ridicule and that's how I treat it."
Bush added: "Tony's great skill, and I wish I had it, is that he's very articulate. I wish I was a better speaker."