The British and Irish governments have until tomorrow to convince the IRA to allow more "transparency" about this week's decommissioning act before a series of crucial Ulster Unionist meetings that will set the tone for the Assembly election.
However, Sinn Féin last night denied that republicans were the cause of the problem.
Mr David Trimble's party has scheduled a meeting of its candidates, which include sceptics Mr Jeffrey Donaldson and Mr David Burnside, as well as a meeting of the executive committee.
These meetings will lay the foundations for the Ulster Unionist campaign for the November 26th elections.
Without the hoped-for deal between unionists and Sinn Féin, the unionist campaign could well turn out to be much more negative than was anticipated.
A reliable British source said last night: "We believe this can be sorted out," but there was no indication of when. It was conceded that the problem "becomes more difficult as time goes on".
Sinn Féin, now involved in a series of contacts in Belfast, Dublin, London and the US, is also wary of a meeting next Wednesday of the Ulster Unionist Council.
This has the power to endorse the party's election campaign strategy and could dash any hope of an election being held in a positive atmosphere.
In turn, this could damage further prospects for the restoration of devolution and the eventual transfer of justice and police powers.
The subsequent ending of the IRA as a paramilitary force would also be jeopardised.
The Sinn Féin president, Mr Gerry Adams, is in contact with Mr Trimble, attempting to discover a unionist perspective on what went wrong on Tuesday.
It is understood he is also trying to determine what degree of transparency unionists require to maximise confidence in the IRA's decommissioning, with a view to passing this on to the IRA.
There have also been contacts between Sinn Féin and Mr Blair, Mr Ahern, the US special envoy, Mr Richard Haass, and key Ulster Unionists.
A trusted Dublin source told The Irish Times last night that the situation could be rescued if the head of the IICD, the decommissioning body headed by Gen John de Chastelain, were given permission by the IRA to divulge further details of Tuesday's act.
Alternatively, the IRA signatory "P O'Neill" could issue another statement providing details of the arms and munitions it put beyond use this week.
A third possibility entails either or both of the two governments being given scope to provide details of Tuesday's decommissioning, which Gen de Chastelain confirmed was the largest so far.
However, a reliable Sinn Féin source told The Irish Times last night that republicans felt they did all that was required of them on Tuesday and therefore that the problem did not lie with them.
The source added that it appeared to republicans that what was being questioned by unionists was not the substance of the IRA's actions but the manner of their presentation.
Mr Ahern, Mr Blair, Gen de Chastelain and his IICD colleague, Mr Andrew Sens, met for an hour at Hillsborough on Tuesday before the general hosted his press conference.
The two prime ministers, The Irish Times was told, were "talked through" the IICD report, but no weapons inventory was handed over and no confidentiality clauses were broken.
Confidentiality between proscribed organisations and the IICD is protected by law, and Dublin fears the entire decommissioning mechanisms would be irreparably damaged, prompting the resignations of Gen de Chastelain and Mr Sens from the decommissioning body, should the secrecy clauses be broken.