More than a third of the Ulster Unionist executive have expressed their opposition to Sinn Fein entering government before any decommissioning by the Provisional IRA.
In a statement yesterday, 42 members of the 112-strong body claimed they had been promised by Mr David Trimble and his senior negotiator, Sir Reg Empey, that any proposals agreed during the Mitchell review would be sent to the executive for approval.
"Many members of the executive are unhappy this did not take place," the statement said. "Forty-two members wish to express their fundamental opposition to Sinn Fein representatives becoming government ministers before a single weapon has been decommissioned or the IRA have demonstrated their commitment to exclusively peaceful means."
Among the signatories are four MPs, the Rev Martin Smyth, Mr William Ross, Mr William Thompson and Mr Jeffrey Donaldson. Other executive members who signed the statement are Mr David Brewster, Ms Arlene Foster, Cllr Jim Rodgers, Cllr Derek Hussey, Mr Peter Weir, Mr Peter King and an Assembly member, Mr Roy Beggs jnr.
In a message to his party, Mr David Trimble said today's UUC meeting would be crucial. "The choice for us is simple - do we want devolution and decommissioning? If we do, this is the only way to get it.
"If we say No there will be no decommissioning and no Stormont government. All the gains secured for unionism in the agreement will be lost and the pain we endured will have been for nothing.
"If we say Yes we get rid of Articles 2 and 3 and the Anglo-Irish Agreement for good. We will return accountable government to Northern Ireland and take control of North-South co-operation."
Meanwhile, the Young Unionists in Upper Bann have expressed concern that some members of the Ulster Unionist Council "might be sleepwalking into a catastrophe".
They said: "The consequences of approving the proposals are catastrophic for the UUP. It would be akin to turkeys voting for Christmas."