Hopes for movement in the peace process rose last night as the Taoiseach, Mr Ahern, and the British Prime Minister, Mr Blair, concluded some seven-and-a-half hours of talks with the leaders of the main Northern Ireland parties at 10 Downing Street.
The cautiously optimistic note was apparently rooted in an unscheduled bilateral meeting between the Ulster Unionists and Sinn Fein, held on the initiative of the parties themselves.
Suggesting that "some progress" had been made, Mr David Trimble, the Ulster Unionist leader, confirmed that the two parties would meet again in Belfast early next week, ahead of further talks in London with Mr Blair and Mr Ahern, possibly on Wednesday.
In what was obviously considered a highly delicate situation, no side was prepared to go into the detail of the various ideas under consideration in an attempt to break the decommissioning impasse, and enable the creation of the Northern Ireland executive.
However, one source expressed the belief that the two sides over a series of meetings had gained a greater understanding of each other's position, and each had a greater belief in the other's commitment to make the Belfast Agreement work.
And there is seemingly a renewed belief in London and Dublin that Mr Trimble and Mr Gerry Adams are both anxious to agree a process which could have the executive up and running by the end of June.
Before flying back to Dublin, Mr Ahern said it had been a "useful" day.
"I wouldn't say a great day but a useful day where we have made a lot of progress. We leave here probably happier that we can return very soon to try to conclude this matter."
Sinn Fein's chairman, Mr Mitchel McLaughlin, was more downbeat in his assessment of progress made.
Repeating that it was up to Mr Blair to resolve the crisis, he said: "Really the only developments . . . have been that there have been eight further murder attacks on nationalists, including Wednesday night's attempt at mass murder in north Belfast.
"We made the case again that you cannot leave the political vacuum to the wreckers, those who want to destroy the process."
Mr John Hume, the SDLP leader, said the two governments and all parties were committed to doing everything within their power to reach agreement: "That was self-evident, but the real answer (as to whether a breakthrough was possible) will be found next week when we resume."
But most striking was Mr Trimble's confirmation of Mr Hume's view that "everybody is very much focused on trying to work through all the difficulties."
While it was "difficult to assess" the progress made in his meetings with Sinn Fein, and he could not say "we have the resolution to hand", Mr Trimble told reporters: "I'm quite sure in my own mind that we will work through all the difficulties, hopefully sooner rather than later. But be in no doubt about our determination."
Mr Trimble, however, stressed that he saw the eventual solution in terms of a development of the "concepts" discussed before Easter which resulted in the Hillsborough Declaration.
The DUP leader, the Rev Ian Paisley, also had talks with Mr Blair yesterday, but his delegation did not meet the Taoiseach.