The British Prime Minister and the Taoiseach will today attempt to chart the next steps in Northern Ireland's political process beyond Mr David Trimble's expected resignation as First Minister.
Mr Blair and Mr Ahern will meet pro-agreement parties at Hillsborough Castle in a fresh effort to break the decommissioning deadlock, or failing that, to lay the basis for ongoing negotiations in Belfast next week.
However, in the presumed absence of a last-minute move by the IRA to begin putting weapons beyond use, there appeared to be a grim acceptance in both capitals last night that Mr Trimble's resignation as First Minister in the Executive would take effect on Sunday.
In an article in today's Irish Times, the Sinn Fein president, Mr Gerry Adams, again asserts his confidence that "the issue of weapons will be successfully resolved".
However, he says Mr Trimble's conclusion that the IRA responds only to pressure is an incentive to that organisation "to prove otherwise".
Mr Adams says the Ulster Unionist leader is making the same mistake as Brian Faulkner, Roy Mason, Margaret Thatcher and others before him.
Mr Adams says: "The UUP can no more pressurise the IRA than the IRA can pressurise the UUP. Politics must be underpinned, not undermined. So Mr Trimble's threat will not work. But if he insists on resigning then resign he will, compelled by his own logic and tactics."
While insisting Mr Blair and Mr Ahern would again "make a very determined effort" in today's talks, British and Irish sources appeared to accept that the public and private positions of the republican movement were one and the same. One gloomy insider said simply: "There isn't anything in prospect to avert David Trimble's resignation at this stage."
Other well-placed sources said that following talks with the parties at Downing Street on June 18th, Mr Blair and Mr Ahern had formed the assessment "that the conditions probably weren't right to bring this thing to a successful conclusion" ahead of Mr Trimble's imposed deadline.
However, conflicting signals from within the Ulster Unionist camp yesterday appeared to have encouraged both governments to believe that the threatened wholesale withdrawal of unionist ministers from the Northern Ireland Executive would not materialise, at least in the immediate aftermath of Mr Trimble's resignation.
That bolstered the assumption of a further six weeks of crisis negotiations in an effort to secure decommissioning before the two governments might have to decide whether to suspend the institutions of the Belfast Agreement, or call fresh Assembly elections both fear could result in further advances for Sinn Fein and the Democratic Unionist Party.
Opinion inside the Ulster Unionist Party is divided as to the tactics to be adopted if Mr Trimble's resignation goes ahead.
Some of Mr Trimble's supporters are in favour of leaving the party's other three ministers in their posts, if only to avoid the blame for forcing the Executive's premature collapse.
Others, in line with Mr Trimble's promise to last week's Ulster Unionist Council of a "graduated response" to the developing situation, apparently favour a phased series of ministerial resignations in an attempt, as one put it yesterday, to "sustain the pressure on Sinn Fein and the governments".
However, there was no official denial of yesterday's report in The Irish Times that the possibility of a collective unionist withdrawal from office had increased following the DUP's indication that its ministers would leave the Executive if Mr Trimble's three colleagues did likewise. And reliable sources last night confirmed that Mr Trimble was still keeping his options open.