Mr David Trimble has warned the British and Irish governments that they risk losing the political process and his leadership of the Ulster Unionist Party if they try to force his hand over the creation of the North's power-sharing executive.
The UUP leader's gloomy assessment of his own position comes just four days before Thursday's new "deadline" for triggering the d'Hondt procedure for the nomination of ministers.
A notice convening a meeting of the Stormont Assembly is expected to be issued on Wednesday. However, it now seems certain that any move to trigger d'Hondt would be preceded by a debate on a DUP-sponsored motion to exclude Sinn Fein from office.
The Assembly's presiding officer, Lord Alderdice, is reportedly satisfied that the motion will attract the necessary support of 30 or more Assembly Members.
While it is thought that Mr Trimble's present inclination would be to abstain, he has told friends he anticipates that "a clear majority of unionists" would back the expulsion move, and fears that following such a development, "his authority would start to ebb away".
Mr Trimble has not yet definitively rejected the proposals in The Way Forward agreed by the British Prime Minister, Mr Blair, and the Taoiseach, Mr Ahern, at the end of marathon negotiations at Stormont 10 days ago.
But as Mr Blair signalled there was "little more' he could do, Mr Trimble said that without firm assurances - either from paramilitaries that they will disarm, or from the two governments and the SDLP that they would "uphold the democratic principle" in the case of default by the IRA - he saw no basis on which to ask his party "to take this risk".
Mr Trimble indicated yesterday that he did not support the imposition of Thursday's deadline for triggering the d'Hondt mechanism to appoint the executive.
"We believe that the people of Britain and Ireland, when they fully understand what is at issue, will come around to our point of view," he said. "That will take some time. And we intend to take that time."
The Taoiseach warned yesterday that postponement of the deadline would create further problems. He said he was "not getting the sense that [postponement] was what people want."
Weekend talks with the SDLP leader, Mr John Hume, and his deputy, Mr Seamus Mallon, failed to produce any fresh indication of the SDLP's attitude to proceeding in government without Sinn Fein should the IRA fail to meet the new decommissioning requirements.
Mr Hume asserted yesterday that "there are no circumstances in which the SDLP would sit in government with any party that is engaged in violence or threatening violence." However, this is not enough for the UUP, which wants an SDLP commitment to continue in government without Sinn Fein if commitments on decommissioning are not met, rather than simply supporting the suspension of the executive.
Mr Trimble now thinks British government legislation to effect the failsafe mechanism, allowing for suspension of the executive and other institutions, may actually increase internal party pressure on him.
The new Bill will be published today and debated in the Commons tomorrow. However, Mr Trimble said yesterday he was not encouraged by what he had seen so far.
The Irish Times understands the draft legislation does not provide for the specific exclusion of Sinn Fein, or for a halt to prisoner releases in the event of default. In addition, it appears the cross-border Implementation Bodies would continue in being for some time after a suspension of other institutions, and that the Anglo-Irish Inter-Governmental machinery would not be affected by a suspension of the Assembly.
On BBC television's Breakfast with Frost, Mr Trimble said: "I see no sign of any commitment by the terrorist organisations to disarm and disband. I see no assurance from the Irish Government, the British government or the SDLP that, in event of their failure, they would uphold the democratic principle.
"The Prime Minister talks about legislation. Well, I look at the legislation to see whether it's fair or not, but so far it doesn't encourage me. No, at the moment I see us invited to take a leap into the dark and I don't see any yet compelling reason why I should sacrifice the democratic principle in this way."
Pressed about the actual "risk" involved in testing the proposed decommissioning arrangements, Mr Trimble replied: "The worst risk we run here is that if I gamble and the gamble is a mistake then we lose the process, and we lose the current leadership of the Ulster Unionist Party. That is the risk."
Last night the hardline MP, Mr Jeffrey Donaldson, warned against a plan being canvassed privately by some of Mr Trimble's allies, which would have him trigger d'Hondt "under protest" while placing a post-dated letter of resignation as First Minister with his party officers.
Under the plan Mr Trimble and other unionist ministers would resign and cause the collapse of the executive if IRA decommissioning had not started by a set date.