The Taoiseach, Mr Ahern, and the British Prime Minister, Mr Tony Blair, will try, today and tomorrow at Hillsborough, to develop "ideas" put forward in Downing Street on Tuesday aimed at finding common ground between Sinn Fein and the Ulster Unionists over how decommissioning might be resolved.
The main focus, sources say, will be on devising a new formula that without actual IRA arms up front would provide the UUP leader, Mr David Trimble, with the "clarity and certainty" he requires to convince his ruling Ulster Unionist Council that IRA violence is a thing of the past.
Senior sources confirmed that a "number of ideas" were put forward and considered during the Downing Street talks on Tuesday, hosted by Mr Blair and Mr Ahern and involving Sinn Fein, the Ulster Unionist Party and the SDLP.
The British and Irish leaders, in company with the rest of the pro-agreement parties, are to embark today and tomorrow on another concerted effort to break the deadlock over arms and devolution. The focus will be on developing the concepts discussed in London on Tuesday.
Sinn Fein and UUP sources said their parties were absolutely committed to ending the political crisis so that the institutions of the Belfast Agreement could be restored.
The Northern Secretary, Mr Peter Mandelson, said in London that the distance between the two sides was narrowing. A Dublin insider agreed.
He acknowledged that speculation was growing that Mr Trimble might be prepared to see the reinstatement of the institutions if the IRA could, in some form of words, provide certainty that its campaign of violence was permanently ended or guarantee that its arsenals were put beyond use.
"But if this is to work whatever is on the table must be enough to allow David Trimble sell it to his party. He has to have clarity and certainty," said the Dublin source.
Nobody was underestimating the scale of this task. One unionist figure said the unionist leadership accepted that it would not get actual IRA decommissioning, adding: "But how do you sell that to the grassroots?"
A senior Sinn Fein member said ending the impasse was still problematic. "There are ideas on the table, and we have our own share of ideas along with the others. We are serious. We want a solution. We know the time is short," he said.
The parties central to these discussions - the two governments, the UUP, Sinn Fein and the SDLP - spoke of the "possibility" of the impasse being ended while cautiously also emphasising that there were no guarantees of a breakthrough.
Mr Ahern and Mr Blair are due at Hillsborough this afternoon accompanied respectively by the Minister for Foreign Affairs, Mr Cowen, and Mr Mandelson.
