Senior members of the Ulster Unionist Party (UUP) will vote tonight on a leadership recommendation to walk away from the North's power-sharing government over claims the Provisional IRA (PIRA) still exists.
UUP leader Mike Nesbitt (pictured) has proposed the exit in response to a police assessment that structures of the supposedly defunct paramilitary organisation remain in place and some of its members were involved in a recent Belfast murder.
Mr Nesbitt has said the revelations have shattered trust in Sinn Féin and the UUP can no longer work in coalition with them.
The endorsement of the UUP’s 110-strong ruling executive at a meeting in an east Belfast hotel is seen by most as a foregone conclusion.
If the move is voted through, the UUP’s one minister in a five-party administration comprising 13 ministers and two junior ministers will formally resign next week. The party will then form an opposition in the Assembly.
A walkout by one of the three minor coalition partners will not in itself trigger the collapse of the Executive, but it will throw its future into serious doubt.
Mr Nesbitt’s announcement has heaped pressure on the Democratic Unionists to follow suit – a move that would bring down power-sharing.
The DUP has so far insisted Sinn Féin should be the party leaving the Executive, not unionists. But the largest unionist party has made clear it will walk away if action is not taken to punish Sinn Féin.
The furore was sparked after PSNI chief constable George Hamilton said the PIRA still exists and some members were involved in the murder earlier this month of Kevin McGuigan, 53, in co-operation with a group styling itself Action Against Drugs.
However, Mr Hamilton said the PIRA is not engaged in terrorism – instead pursuing peaceful, political republicanism – and said there is no evidence the McGuigan killing was sanctioned by the IRA leadership.
Mr McGuigan was suspected by some in the republican movement of involvement in the murder of former IRA leader Gerard “Jock” Davison in Belfast three months ago.
Police believe his killing was a revenge attack by Mr Davison’s republican associates.
Sinn Féin, which refutes the claim the IRA still exists, has accused the UUP of contriving a crisis in a bid to outflank the DUP ahead of next year’s Assembly poll.
The UUP has also found itself accused of hypocrisy by critics who have pointed to the fact it co-operated with political representatives of loyalist paramilitaries as part of a pan unionist/loyalist approach to a parading dispute last year.
It is almost 20 years since the Provisional IRA’s last ceasefire and a decade on from the supposed decommissioning of its weapons.