The Taoiseach and British Prime Minister will tomorrow discuss the detail of moves which they hope would pave the way for a dramatic IRA gesture and the return of the Ulster Unionist Party to the North's suspended power-sharing institutions.
With the Sinn Féin leadership billing tomorrow's Downing Street meeting as possibly the most important of the entire peace process, Mr Ahern and Mr Blair will seek to devise an outline deal to break the deadlock.
Well-placed sources said last night that they hope this week's series of talks will produce a basis for a final phase of negotiations to restore the North's political institutions ahead of Assembly elections scheduled for May. Government sources hope for a deal by mid-February, although talks could drag out longer.
The Sinn Féin president, Mr Gerry Adams, yesterday criticised as "unhelpful" speculation that the IRA is planning a historic gesture such as a "standing down" of the organisation. However, speculation persists that the IRA is prepared to make a significant declaration to assure people that it intends to be inactive in the future, coupled with a substantial movement on paramilitary weapons.
However, any such move would only come as part of a deal involving what Mr Blair has called "acts of completion" on all sides. Tomorrow's Downing Street talks will see discussion of changes sought by republicans including further police reform, the dismantling of British army bases and more progress on equality and human rights as well as some means of ensuring the suspended political institutions - if restored - will not be vulnerable to a further series of suspensions. Mr Ahern will meet the Ulster Unionist Party leader, Mr David Trimble, in London tomorrow in advance of his meeting with Mr Blair. This discussion, following his two-hour meeting with Mr Adams and Mr Martin McGuinness in Dublin yesterday, will give him a clear picture of what is possible before he goes to Downing Street.
There, the two leaders will discuss the possible "acts of completion" that could be made by the British government.
The Government is anxious for the talks not to drag out as this could run the risk of Mr Blair being distracted by the growing Iraqi crisis. The Taoiseach is to meet the SDLP leader, Mr Mark Durkan, in Dublin today to assess the prospects for progress.
The Sinn Féin leadership yesterday suggested that progress would depend on what was on offer from the British government in the coming weeks. According to Mr McGuinness: "If this is going to work we are going to see, over the course of the most critical six to eight weeks in the history of Ireland in 100 years, whether or not we are going to be dealing with a British government that is serious about implementing the Good Friday agreement."
Mr Adams said that tomorrow's Downing Street meeting "could be the most important in the history of the peace process". He said he wanted to see "evidence from the British Prime Minister that he is totally committed to implementing the Good Friday agreement in full".
In making demands for the implementation of the Belfast Agreement, Sinn Féin are seeking the full implementation of promised police reforms, demilitarisation and various human rights and equality moves.
However, it is the scale of what is on offer from the IRA that will be crucial to the Ulster Unionist Party's decision on whether to return to the power-sharing institutions.
Well-placed sources said yesterday that the IRA was highly unlikely to say it would "disband" or "stand-down". However, some other formulation indicating a clear commitment to the ending of all paramilitary activity and possibly a means of verifying this ending of activity have been discussed in recent weeks.
If talks continue in the coming weeks they will also have to seek some mechanism to ensure that the political institutions, if restored, are not suspended again as a result of UUP action.
Mr Adams said yesterday that if unionists agreed to participate again in the institutions, "how long will it be for"? This week's meetings will also deal with the division between parties over whether fresh Assembly elections should go ahead in May.