The Taoiseach, Mr Ahern, and the British Prime Minister, Mr Tony Blair, will meet in Downing Street today in a renewed bid to advance the peace process before the May 22nd deadline for decommissioning.
The deadline was set as part of the Belfast Agreement, as the time by which paramilitary weapons were to have been taken out of use.
The two government leaders will hold separate meetings with the Ulster Unionist Party, Sinn Fein and the SDLP in an effort to agree a formula to lead to the restoration of the Northern Executive and institutions. The Minister for Foreign Affairs, Mr Cowen, and the Northern Secretary, Mr Peter Mandelson, will also attend.
An Irish Government source said the talks would have two elements. One will be aimed at defining the UUP bottom line for the restoration of the institutions and decommissioning, and to see if Sinn Fein is prepared to try to bring the IRA forward to meet UUP demands.
The second element will centre around getting agreement from the parties on proposals to deal with outstanding issues under the Belfast Agreement, such as the criminal justice system, demilitarisation, the Patten report on the RUC, and human rights.
"We still have no indication how prepared both sides are willing to stretch," the Government source said.
Mr Ahern and Mr Blair were in telephone contact over the weekend and have met twice recently in a push to break the deadlock. Officials from both governments have been working around the clock in the last week to put together a plan to win the support of Sinn Fein and the Ulster Unionists. Both leaders have left their diaries flexible to allow for further talks this week.
However, both nationalist and unionist sources last night said they believed there would be no progress today and that the talks were effectively for public relations.
The Ulster Unionist deputy leader, Mr John Taylor, said:
"Whilst the IRA and Sinn Fein continue to say there will be no decommissioning, I have no reason to be optimistic about the outcome of these talks.
"At best, they might inject a sense of realism into the attitude of Dublin and any others who retreat in face of IRA obduracy. For reasons known only to the Dublin Government, an optimistic spin is being given by Dublin to the outcome of these talks."
Mr Taylor said the sole reason for the stalemate was the failure of the Provisional IRA to decommission. He said Dublin must put pressure on the paramilitary group and on Sinn Fein.
Sinn Fein MP Mr Martin McGuinness said his party was committed to saving the agreement and had been "in contact with all the pro-agreement parties and are in daily conversation with both governments.
"It remains our firm view that British government policy and its approach to resolving the current crisis are the key to any possibility of a breakthrough." He said Mr Blair must ensure the full implementation of all outstanding aspects of the agreement including policing, demilitarisation, justice and equality matters.
Mr Sean Farren of the SDLP negotiating team said the next fortnight was crucial for the agreement. "For the sake of all the people of Northern Ireland, the opportunity to ensure its full implementation must not be lost."
He said all the pro-agreement parties appeared anxious to have it fully restored. Sinn Fein had indicated recently it was anxious to explore new ways of making progress on decommissioning, he said.
"Actually achieving decommissioning is more important than being seen to noisily demand it. It seems to me that sometimes those who make noisy demands are actually knowingly decreasing the chances of achieving it for their own selfish political ends."
Mr Farren said the Executive and Assembly should be restored immediately as "a great desire exists throughout the whole community to have the institutions in action once more".