The Taoiseach, Mr Ahern, and the British Prime Minister, Mr Tony Blair, are to hold a "key" meeting in Downing Street on Wednesday to assess the prospects of Sinn Féin and the DUP endorsing Dublin and London's blueprint for restoring devolution.
Wednesday's meeting is viewed as Mr Ahern and Mr Blair making it clear to the DUP and Sinn Féin that they are serious in their requirement for a speedy response to their proposals for restoring the Northern Executive and Assembly. One senior source last night described it as a "key" encounter.
The Taoiseach and Prime Minister may use the meeting to devise their "Plan B" for dealing with the possible failure of these talks - that is, if there are no indications of definitive answers being forthcoming quickly from the DUP leader, the Rev Ian Paisley, and the Sinn Féin president, Mr Gerry Adams.
The Irish and British governments have effectively set this coming Friday as the date for a response from the DUP and Sinn Féin to their proposals. While this deadline could slip into next week, both Dublin and London sources were adamant Mr Ahern and Mr Blair wanted a definitive response quickly. Sources said the two leaders were prepared to allow the DUP and Sinn Féin some time beyond Wednesday for responding to their proposals, but that Mr Ahern and Mr Blair would formulate new proposals to keep the process moving forward if their blueprint were rejected.
This could involve a number of options, including calling Assembly elections or strengthening the British-Irish dimension of the Belfast Agreement to ensure that what the governments believe is a firm offer from the IRA to decommission and end activity is not lost, sources indicated.
Mr Ahern said he was "upbeat" about the chances of the whole island of Ireland having an historic and peaceful Christmas, while the Northern Secretary, Mr Paul Murphy, said he believed the politicians were serious in their attempts to achieve a breakthrough.
Meanwhile, Irish and British officials will continue an intensive round of discussions with senior DUP and Sinn Féin politicians this week to try to deal with the points of clarification both parties have raised.
The Sinn Féin president in an article in today's Irish Times described the governments' proposals as "work in progress" and said if this initiative failed because of "rejectionist" unionism's refusal to share power with nationalists, then "power sharing between the two governments" was the way forward.
Senior sources, meanwhile, have admitted to anxieties that purported divisions in the DUP could jeopardise the possibility of a deal. Sinn Féin's chief negotiator, Mr Martin McGuinness, expanded on this matter on Saturday when he said it was the DUP, not the IRA, which was preventing agreement.
"The problem at this particular time is whether or not the Democratic Unionist Party are going to make up their minds as to whether or not they are going to do the business, and do the business now," he told BBC Radio Ulster's Inside Politics programme.
There are similar concerns in Dublin and London, it is believed. Some sources argue that the DUP deputy leader Mr Peter Robinson is willing to do a deal on the basis that he believes he has a firm offer from the IRA to fully decommission and end activity, but that the DUP leader, the Rev Ian Paisley, is uncertain whether now is the time to do business with Sinn Féin.
A DUP spokesman yesterday dismissed the talk of tensions and divisions within the party. "They are wholly inaccurate. The Democratic Unionist Party is absolutely determined in where it is going and absolutely united in what it is going to do," he said.
