The North's First Minister and Deputy First Minister may be forced to cut short a planned trip to the US as the crisis deepens over decommissioning paramilitary weapons and the creation of the Northern Ireland executive.
Mr David Trimble and Mr Seamus Mallon are due to join the Northern Secretary, Dr Mo Mow lam, and Britain's Chancellor, Mr Gordon Brown, at the start of a 10-city promotional tour in the US next weekend.
However, a possible change of plan was signalled last night by Mr Mallon as he prepared for a potentially fraught meeting with Mr Trimble at Stormont later today and for "in-depth" talks with the British Prime Minister, Mr Tony Blair, in Blackpool tomorrow or Wednesday.
The meeting between the First and Deputy First Ministers will be their first since Mr Mallon's public confirmation of serious differences between them over the timing and conditions for the creation of the institutional structures to be established under the Belfast Agreement.
Mr Trimble and Mr Mallon are scheduled to make a joint appearance before the Labour Party conference on Wednesday, where they can expect enthusiastic acclamation for their roles in securing the agreement. However, a measure of the tension between them over the next steps in the peace process came with strong indications last night that they are likely to hold separate, one-to-one meetings with Mr Blair during their two-day stay in Blackpool.
Mr Blair will also have separate talks this week with the Sinn Fein president, Mr Gerry Adams, who yesterday met the Taoiseach, Mr Ahern, to express the "extreme concern within Sinn Fein at the refusal of unionists to keep their word on implementing the terms of the agreement".
In a statement after the meeting, Mr Adams's spokesperson said: "We need to see all aspects of the agreement implemented and at this time this means the speedy establishment of the executive."
Mr Mallon told The Irish Times last night he thought the proposed US visit might have to be cut short because "it's a long whack out of what we have left" - a direct reference to the October 31st deadline for agreement on areas of North-South co-operation and implementation bodies to be completed by the Government and the interim Northern Ireland administration.
In common with Mr Ahern and Mr Adams, Mr Mallon has rejected Mr Trimble's argument that they, as First and Deputy First Ministers, can represent the interim administration at initial meetings of the North-South Ministerial Council and the British-Irish Council.
On decommissioning, Mr Mallon said "a process has got to be found which will allow the structures to be created and the process to develop".
Asked if that meant a process guaranteeing that actual decommissioning would occur, Mr Mallon replied: "A process to deal with decommissioning while al lowing the agreement to be operated and implemented."