Although UUP leader Mike Nesbitt announced on Wednesday that his party intends to pull out of the Executive, the formal decision will be taken on Saturday night at a meeting of the party executive in east Belfast.
The meeting of the party’s ruling body will take place at the Park Avenue Hotel in east Belfast – a favoured location for the DUP and close to both parties’ Belmont headquarters.
The outcome of the meeting, which begins at 6pm, is expected to be a formality.
The UUP leader was careful to consult colleagues across the party, and although support for the decision is not unanimous among the party membership, it appears to have been overwhelmingly popular.
If the meeting ratifies the leader’s proposal that Regional Development Minister Danny Kennedy quits the Stormont Executive, that is unlikely to happen until at least Tuesday as Monday is a bank holiday.
Mr Kennedy will formally write to the First and Deputy First Ministers to resign.
Under Section 18 the Northern Ireland Act 1998, Mr Nesbitt will then have seven days to nominate a replacement. However, it is not clear whether that period can be shortened if Mr Nesbitt immediately indicates – as he will do – that he will not be replacing Mr Kennedy.
At that point, the Assembly’s Speaker, Mitchel McLaughlin, will have to convene a meeting of the Assembly, which is due to return from its recess in just over a week’s time on September 7.
It is at that point that Peter Robinson will have to decide whether he is staying in the Executive.
Under the D’Hondt mathematical formula which sees Executive seats shared out according to parties’ size, the DUP are next in line for a ministry.
If Mr Robinson refuses to take the seat, it would then go to a nationalist party, but in reality Mr Robinson is likely to either appoint a DUP minister to the vacant position or lead his entire ministerial team out of the Executive.