Significant differences have resurfaced between London and Dublin about whether an alternative to Mr David Trimble's unionist leadership might now represent the best chance of saving the Belfast Agreement.
This was confirmed last night as Mr Trimble's Ulster Unionist Party faced the possibility of a formal split - and a consequent realignment of unionist forces - in the aftermath of Monday night's crucial meeting of the Ulster Unionist Council.
Sources close to Mr Trimble and his main leadership challenger, Mr Jeffrey Donaldson, appear agreed that the result of the vote on a motion rejecting the British-Irish Joint Declaration as a basis for restoring the Stormont Assembly and Executive is in the balance.
One usually reliable anti-agreement source told The Irish Times that, while he thought Mr Donaldson had made "a huge mistake" in saying he would consider his position if the vote went against him, there had been a sharp change in the unionist mood and that the Lagan Valley MP might carry the day.
Against that, other senior party sources suggest delegates might find a lack of clarity on the issues raised by the Joint Declaration and conclude that Mr Donaldson is wrong to make this the "defining moment" for unionism. In addition, even some natural Donaldson allies say privately that his threat to leave the party will have damaged any claim he might subsequently make to be a "unifying" alternative to Mr Trimble.
Mr Donaldson maintains he has not made up his mind about any course of action if he suffers a policy defeat on Monday. However, his Irish Times interview yesterday has strengthened the belief that - contrary to suggestions by critics - he is prepared to quit the UUP.
The key question in that event is with what force of numbers Mr Donaldson might leave, and whether he would then launch a new unionist party which would fight any Assembly election in coalition with the DUP and other groupings on a commitment to force a renegotiation of the agreement.
In his interview yesterday Mr Donaldson said that the agreement was "flawed" and that "there does need to be a renegotiation." Despite this, some senior Dublin officials have apparently concluded that a majority unionist bloc effectively led by Mr Donaldson and the deputy leader of the DUP, Mr Peter Robinson, might offer the best prospect of reviving the political process. They also calculate that, despite the rhetoric of renegotiation, such an alternative unionist leadership would eventually make a political accommodation with republicans and nationalists.
British sources say this line of thinking resurfaced - in official rather than ministerial circles - in the aftermath of the decision by the Prime Minister, Mr Tony Blair, to back Mr Trimble and postpone the Assembly elections because of the absence of satisfactory IRA "acts of completion".
The sources say disappointment about the election, coupled with irritation with Mr Trimble's personal style and weariness with the recurring threats to his position, have strengthened the tendency inside the Department of Foreign Affairs at official level "to have an election, shake everything up and see where things stand at the other side of it."
However, the British assessment - shared by 10 Downing Street and the Northern Ireland Office - is that Dublin officials "don't seem to understand what people like Jeffrey Donaldson and Peter Robinson actually believe and want."
London maintains that Mr Trimble does still represent the majority of unionists, who, polls say, want to support the agreement provided the issue of paramilitarism is resolved.