The Ulster Unionist executive has endorsed the party's decision to vote against the devolution of policing and justice powers to Northern Ireland.
The assembly is to vote on whether the powers should be devolved on Tuesday.
Earlier on Monday, the UUP accused Northern Ireland Secretary Shaun Woodward of political and emotional blackmail ahead of Tuesday's vote.
Danny Kennedy said he had linked the vote to the anniversary of the murder of Constable Stephen Carroll.
The vote takes place exactly a year after the police officer was murdered by the Continuity IRA in Craigavon.
Mr Woodward said transferring justice powers on Tuesday would send an important message to those responsible for his death and dissident republicans in general.
But Mr Kennedy, the UUP's deputy leader, said the secretary of state was guilty of "political and emotional blackmail" and called on him to consider his position.
The UUP has been refusing to endorse the Hillsborough Agreement, insisting that matters such as education, parading and "the dysfunctional nature of the current executive" must be addressed.
On Monday night, former DUP leader Ian Paisley said the UUP would be making a "colossal mistake" by not backing the deal.
Mr Paisley was speaking to DUP members in Ballymena as he announced his retirement as MP for north Antrim.
The DUP selected his son, Ian Jnr, as its candidate in the forthcoming Westminster election at the same meeting.
Meanwhile, an opinion poll commissioned by the Northern Ireland Executive has indicated that the majority of people in Northern Ireland favour devolving justice powers.
It also suggested that 70% of unionists favour Northern Ireland politicians being in charge of policing issues, compared to 83% of nationalists.
Copyright (c) 2010 BBC News Northern Ireland
