The naming of ministers-designate to the new Northern executive is likely to take place today as the first step in implementing the Belfast Agreement and bringing into force the widest range of constitutional and political changes since the Anglo-Irish Treaty of 1921.
There are continuing fears that legal difficulties over the position of Mr Seamus Mallon could block the ministerial nominations at the Stormont Assembly. The SDLP MP and Assembly member offered his resignation from the post last July and it is seen as critical that this should now be declared null and void.
An election for the post of Deputy First Minister would need the votes of over half the unionists in the Assembly, as well as half the nationalists, and this support would not be forthcoming on the unionist side.
However, Mr Sean Neeson, of the Alliance Party, has tabled a motion to the effect that, notwithstanding his offer to resign, the Assembly wishes him to hold office as Deputy First Minister.
This motion would only require the support of 40 per cent of unionists, provided there was backing from 40 per cent of nationalists and an overall 60 per cent majority in the Assembly.
A change in Standing Orders from the Northern Secretary, Mr Peter Mandelson, is also expected to be introduced, which may facilitate the implementation of Mr Neeson's motion. Pending devolution, the British Government is responsible for the day-to-day rules governing the Assembly.
Anti-agreement unionists could decide to take legal action challenging the moves in relation to Mr Mallon. "We have not ruled out taking legal action," Mr Ian Paisley jnr, of the Democratic Unionist Party, said last night. "It is one of the most underhand acts ever to come out of this process."
The DUP has also tabled a motion to exclude Sinn Fein from office on the grounds that it is not a democratic party, but support from a member of the UUP Assembly team will be needed to secure a debate.
There was speculation that the nomination of ministers might be delayed as late as midnight, but there were strong indications that the Northern Ireland Office intends that the procedure be gone through, whatever the hour.
There was continuing republican unease over the motion passed at Saturday's Ulster Unionist Council meeting in Belfast. The motion stated: "The Ulster Unionist Council authorises the Leader and the Ulster Unionist Assembly Party to proceed as outlined in the Leader's Report and instructs the President to reconvene the Council in February 2000 to take a final decision." It was carried by 58 per cent to 42 per cent - 480 votes to 349.
The setting of a February deadline for decommissioning clearly came as a surprise to Sinn Fein and there were swift objections from the party. Mr Martin McGuinness said: "It was not a decisive step forward. It was a jump forward to uncertainty."
Providing for the council to be reconvened in February was seen as a move by Mr Trimble to avoid a split in the party. The "No" lobby in the UUC will be attempting to mount a further challenge at the February meeting.
Mr Trimble also lodged a letter with the president of the UUC, Mr Josias Cunningham. It was understood to contain a pledge to resign in the absence of progress on decommissioning by some unspecified date. Similar letters are to be requested from UUP ministerial nominees.
A devolution order is expected to be laid before the Houses of Parliament at Westminster tomorrow. The first full meeting of the devolved executive is scheduled for Thursday, to be immediately followed by the appointment of an IRA interlocutor to the decommissioning body.
The amended versions of Articles 2 and 3 of the Republic's Constitution will take effect on Thursday.