If Gerry Adams and David Trimble are calling this right, we are on thebrink of something bigger than the Belfast Agreement, writes LondonEditor, Frank Millar.
Following Monday's Downing Street summit the Sinn Féin president described the ongoing attempt to salvage the 1998 accord - and the challenge to unionists and republicans, as well as both governments - as unprecedented. We have every reason to believe it must be so.
The Irish Times reported on Tuesday that Sinn Féin and the Ulster Unionists had made significant progress toward establishing an agreed basis for fresh Assembly elections and that senior unionists were privately admitting for the first time it was now a question of "when" and not "whether" the twice-postponed election will take place this year.
The talks between the two parties in the intervening days have reinforced the sense that Mr Trimble hopes, and expects, any day now to conclude an agreement with Mr Adams presaging a return to power-sharing government following an Assembly poll some time next month.
Yet the Ulster Unionist leader has stipulated terms from which retreat now would seem only to ensure electoral disaster for his party and personal humiliation and opprobrium for himself. Those terms are rooted in Mr Tony Blair's famous "acts of completion" speech a year ago. Mr Trimble only recently told MPs this was a euphemism for complete decommissioning and "effective disbandment" of the IRA.
In other words, Mr Trimble regards the present negotiation as about nothing less than completion of the unfinished business of 1998: bringing an end to physical force republicanism and, crucially, the opening of a new chapter in which the IRA this time buys in to the political process which would return Sinn Féin ministers to office.
This last point is the essence of the matter; for the problems which have bedevilled the process since 1998 (from the unionist perspective) derive from the fact that the Provisionals were not a party to the agreement. And not just from the unionist perspective.
This is what lay behind Mr Blair's insistence last October: "The crunch is the crunch. There is no parallel track left. The fork in the road has finally come . . . We cannot carry on with the IRA half in, half out of this process. Not just because it isn't right any more. It won't work any more."
For sure, there are other major issues on the table. As Mr Trimble has discovered previously to his cost, it is never a single item agenda when he seeks to persuade republicans to declare "the war" over and to decommission their weapons in a credible and timetabled process with enough transparency to sustain public confidence and belief.
Of these, the most difficult and politically dangerous (from both the Ulster Unionist and Sinn Féin perspectives) is policing. For here, the scale of Mr Adams's ambition is no less than Mr Trimble's. The project, if successful, would see Sinn Féin going within months to a special ardfheis to propose joining the policing boards in the context of an agreed process. This would see policing and justice powers devolved to Stormont by the mid-way point in the next Assembly.
Sinn Féin leaders would ultimately encourage the sons and daughters of former IRA activists (and, who knows, perhaps some former activists themselves?) to join the PSNI and participate in the policing of a still-partitioned Northern Ireland.
This is a potential minefield for Mr Trimble. Already the word is "out there" in Unionistland that he will deliver Sinn Féin's Mr Gerry Kelly as Minister for Justice in little over two years' time.
You only have to raise the possibility to understand the enthusiasm of Dr Paisley and Mr Peter Robinson for the electoral fray. But then, as Mr Blair said last October, you only have to raise the possibility to realise its absurdity unless the IRA goes out of business.
The Prime Minister said: "For republicans there is one very simple thing moving them in the direction of progress. Leave aside the disagreement over aspects of policing. They want to join. But the concept of republicans on the policing board, of young republicans becoming police officers, while maintaining an active paramilitary organisation, outside of the law, only needs to be stated to be seen as an absurdity. There can't be two police forces."
Intriguingly, Mr Blair's words raise the possibility in the minds of some close observers of the IRA continuing as an inactive paramilitary organisation. In which context, Mr Adams's recent suggestion "better the IRA you know" might have had particular and intended significance. Perhaps they think to do what was done to the RUC: incorporate the IRA in the "title deeds" of Sinn Féin the Republican Party and then consign the organisation to the history books, reduced to acts of recreation and remembrance.
Again, you only have to raise these questions to realise why Mr Trimble and Mr Adams might think better of seeking to resolve fully the policing issue ahead of an election. However, Mr Blair's words make it clear that it can only be so when the IRA does indeed become history.
It is, therefore, no exaggeration to say that if the Adams/Trimble negotiation results in agreement, we are on the verge of something truly massive. Moreover - whatever the words and decommissioning deeds, accompanied by renewed British commitments on demilitarisation and the implementation of the British/Irish Joint Declaration - any instant gratification must give way to a still-more hazardous process.
In the meantime there is the small matter of an election which the Irish Government apparently now believes will see Sinn Féin eclipse the SDLP, and which could easily kill off Mr Trimble.
Certainly the DUP does not believe Mr Adams will deliver the end of the IRA for an embattled Ulster Unionist leader they intend to supplant come polling day. Mr Trimble's internal dissidents, likewise, relish the prospect of an election in which they will stand in opposition to their leader for an Assembly in which they would coalesce with the DUP to force a renegotiation of the agreement. And even some pro-agreement unionists are already looking beyond polling day to reviving their plan for a Reg Empey/Jeffrey Donaldson "dream ticket" succession to the Trimble leadership.
Given the near dysfunctional state of the UUP, and the history of the past 5½ years, it is hardly surprising many commentators are convinced Mr Trimble will get either no deal or a bad one, and that Sinn Féin and the IRA will hold back on the big decisions until they see which unionist leadership emerges from the election.
This, it must be said, would be in character. At the turn of the year the question was whether Sinn Féin would do enough to ensure the election but not enough for Mr Trimble. We know the answer they delivered last April. We also know that Sinn Féin and the Irish Government were astounded when Mr Trimble called a halt to the proceedings and prevailed on Mr Blair to cancel the election.
Now that the British system has virtually conceded the election - appearing, in the process, to circumvent and undermine Mr Trimble's negotiation with the republicans - the question again arises: why would Sinn Féin now join a "save Dave" campaign? Certainly some prominent members of Sinn Féin remain antagonistic to the UUP leader; continue to question his commitment to the agreement as well as his ability to deliver; and evince confident belief that DUP modernisers led by Mr Robinson will eventually do the business with them.
That said, it is not clear that these individuals reflect - or even fully grasp - the calculations of their leaders. For some time now evidence has been building that Mr Adams has studied the form and character of the putative alternatives and concluded that Mr Trimble - for all that he drives republicans mad - is the best bet for a stable agreement.
Mr Adams accepts that David Trimble wants the Belfast Agreement to work. Mr Trimble, likewise, accepts the bona-fides of Mr Adams and Mr Martin McGuinness. That it has takenso long to reach this point - and the recent, symbolically important handshake - is a symptom of the fact that there was no Ulster Unionist/Sinn Féin dialogue during earlier stages of the IRA ceasefire or during the process leading to the accord. But this is where things now stand.
Looking to the election ahead, Mr Adams cannot know if the Trimble leadership will prevail in a new Assembly. However, he surely realises that if he holds back now he will break Mr Trimble and, almost certainly, the agreement as well.