Martin McGuinness accused the Ulster Unionists today of opposing a deal to devolve policing powers to Northern Ireland for cynical party political reasons, as a crunch debate on the transfer began at Stormont.
The Sinn Féin Deputy First Minister heavily criticised the UUP's stance as he tabled a motion that, if passed, will see justice responsibilities handed over to the powersharing administration in April.
The UUP is the only party that has signalled its intention to vote against the proposals outlined in the landmark Hillsborough Agreement, insisting the Stormont Executive is not operating effectively enough to warrant taking on the powers.
"The UUP declared last night that they will not support this resolution," said Mr McGuinness.
"That saddens and disappoints me, they are opposed in my view to the transfer for cynical party political reasons."
Hours before the Deputy First Minister turned on his unionist rivals, the widow of a police officer murdered by dissident republicans made a dramatic plea today for all politicians to back the deal.
Kate Carroll, whose husband Pc Stephen Carroll was shot dead by the Continuity IRA a year ago today, said all parties should back the plan.
In a surprise call to a radio show, she said: "This morning has been very, very hard for me, and I would just ask everyone in Stormont to please get on with their job."
The UUP is also under international pressure to back the deal.
Former US president George Bush phoned Conservative leader David Cameron asking him to intervene, given the Tory Party's electoral pact with the Ulster Unionists in the North.
But today Mrs Carroll told the UUP: "I am pleading on this day that is so important to me that it's not worth it. Life is too short. It is heartbreaking that I have to get on this morning to please ask the politicians to get on with their job."
The UUP has claimed the executive must sort out other outstanding matters - such as the long-standing row over post-primary school transfer arrangements - before it can take on law and order functions.
Mr McGuinness questioned the logic of this stance as he commended the Hillsborough deal to the Assembly.
"The UUP are on record as stating that they will not support the election of a local minister to oversee the administration of policing and justice until there is agreement to test 10 and 11-year-old children to determine which school they will attend," he said.
"I have to say that these are the most dysfunctional political positions I have ever come across."
He added: "The Hillsborough Agreement provided an opportunity for a new start. The process we are engaged in is one in which no one single party can dominate and control, it is one which we must all work together for the common good, it is one which we must work together to maintain the political stability which will deliver prosperity, quality public services and investment.
"I acknowledge that this is a challenge to us all but it is one to which we all must rise. We need to put aside party political posturing and to begin an era of joint and equal working."
The DUP and Sinn Féin have the strength to pass today's measures, but a rejection from the UUP will deprive them of the unanimous support they and the British and Irish Governments have sought for the deal.
Ulster Unionist deputy leader Danny Kennedy confirmed in the Assembly that his party will not endorse the Hillsborough Agreement when the vote takes place later today.
He attacked the deal's plan to devolve policing and justice powers, but he also alleged that a UK government side deal with republicans to see the Army removed from the North would emerge before October.
But while he challenged DUP members who were sceptical over the blueprint to voice their concerns, he reserved his strongest criticisms for Sinn Féin and Northern Ireland Secretary Shaun Woodward.
He said Mr Woodward's attempts to persuade the party to back the deal had amounted to undue pressure.
"The Secretary of State, in my view, has behaved disgracefully, particularly over recent days, and his attempts to bully and to bribe and to blackmail this party, I think, has abused the high political office that he holds," said the UUP representative.
"He should pack his bags well in advance of the forthcoming general election."
Mr Kennedy said his party would not endorse the motion which paved the way for the passage of the devolution legislation.
"We need to address seriously the issues that confront this Assembly, confront our people, the issue of the economy and jobs and education and health.
"I say the Ulster Unionist Party is right when it stands back and holds back its position today."
Leader of the SDLP Margaret Ritchie said her party would vote in support of the devolution of policing and justice powers later today, but she was highly critical of the wider Hillsborough deal.
She condemned plans to step outside the normal power-sharing selection process for ministerial posts, with the move set to see the smaller Alliance Party emerge as an agreed candidate for the new post of Justice Minister.
She also criticised claims by Mr Woodward that failure to back the deal sent out a message which might give succour to dissident groups opposed to the peace process.
Ms Ritchie said the DUP and Sinn Féin had failed to allow her party access to key elements of the deal.
"So, with Hillsborough, we have a new kind of agreement," she told the Assembly.
"Something is agreed when the DUP/Sinn Féin say it is agreed - but no-one is allowed to see the evidence.
"There is little integrity in this process and it will ultimately unravel.
"And, in the next days and hours, the suggestion that anyone who is not cheerleading for Hillsborough is somehow recklessly ignoring the recent upswing in dissident republican violence is, again, low-rent politics.
"The remarks attributed to the Secretary of State in this regard have been unacceptable."
Democratic Unionist member Ian Paisley Jnr, with his former First Minister father Ian Paisley sitting on the benches in front of him, referred to Mrs Carroll's powerful contribution as he made an impassioned appeal to the UUP to think again.
"A widow who could have taken a very, very different approach to life, said 'Get on with it. Get on with it for the memory of my husband. Get on with it for the memory of ordinary Ulster men and Ulster women'," the North Antrim representative said.
"That's the challenge to every man and woman in this House: to pick up the gauntlet, to take this House forward and to rule this divided country with a bit of energy, with a bit of hope and try and bring a bit of harmony to this place.
"Is this House listening to the crying words of men and women outside this chamber or are we in wrecking mode? That is the answer that Ulster awaits today."
Alliance Party leader David Ford, who is the favourite to be Justice Minister if the powers are devolved, said the move would cement the peace process.
"There is no doubt that the devolution of justice is the last challenge that we face as an Assembly," said the South Antrim MLA.
"It is what brought down the institutions in this place in 1972, it was what was too difficult to deal with in 1998 (in the Good Friday peace agreement) and it is what will be a sign that we can actually start to make progress at this stage.
"In fact, it will be the biggest change in the devolution arrangements of any of the three devolved nations (Northern Ireland, Scotland and Wales) since 1998.
"I believe members of this House need to listen to the community. They need to listen in particular to those who are involved in the justice system about the importance of getting this devolution to take place and to show that we can deliver in here for all our people."