Mr David Trimble last night called off unity moves inside his party and set the scene for a showdown with Mr Jeffrey Donaldson at tomorrow's Ulster Unionist Council meeting.
And there was bitter recrimination last night that Mr Trimble had made his move even as two of his Assembly colleagues, Mr Fred Cobain and Mr Danny Kennedy, continued negotiations with Mr Donaldson on the possibility of an agreed resolution to put before the party delegates.
The Irish Times understands that the trio - who have been in talks since last Friday - had "narrowed the differences" and concluded their meeting just before six o'clock with an agreement that Mr Donaldson and Mr Trimble should meet later this morning.
But as Mr Cobain and Mr Kennedy travelled to Stormont to put this proposition to Mr Trimble, they heard media reports of a press conference at which Mr Trimble denounced Mr Donaldson's "Christmas wish-list" and dismissed the idea of a specific deadline for IRA decommissioning as "counter-productive", saying: "The problem with a deadline is it is telling republicans how they can escape the pressure."
The idea of a fixed cut-off point for Ulster Unionist withdrawal from the power-sharing Executive in the continued absence of IRA decommissioning has been central to the discussions between Mr Cobain and Mr Kennedy and Mr Donaldson. In their most recent proposal to Mr Donaldson, the two Assembly members proposed a three-point package. This would have entailed a demand for a "moratorium" on the Patten policing reforms; immediate withdrawal from North/South institutions; and a meeting of the UUC in early January to confirm withdrawal if decommissioning had not begun by Christmas.
It is understood the talks were supervised by the Enterprise Minister, Sir Reg Empey, and that Mr Trimble - while not directly involved - was kept fully informed. Last night's meeting with Mr Donaldson was held at the party's Glengall Street headquarters.
It is known that concern had grown throughout the week among other leading members of the Trimble camp about the direction of the discussions with Mr Donaldson. And when it was confirmed last night that the talks with the Lagan Valley MP were "finished", it seemed to represent a clear victory for those pro-agreement forces who argue that a unionist-imposed deadline would see unionists take the blame for the inevitable collapse of the Belfast Agreement.
However, the confusion about Mr Trimble's final strategy for tomorrow's meeting continued, as it was confirmed to The Irish Times by usually reliable sources that the question of a cut-off point for participation in the Executive had not been resolved.
With his deputy, Mr John Taylor, publicly committed to a Christmas deadline for decommissioning, the possibility remained that the fallout from the Donaldson unity talks could cost Mr Trimble the support of a number of previously loyal members of his Assembly party.