Mr Peter Mandelson was caught in Sinn Fein/Ulster Unionist crossfire last night, as republicans cast doubt and confusion on what was presumed to be a key element of the devolution/decommissioning deal concluded last week in the Mitchell review.
The Ulster Unionist deputy leader, Mr John Taylor, said the Secretary of State had "failed to reassure unionists" with a Commons statement in which he outlined the so-called "default mechanism" to ensure decommissioning would follow the appointment of the power-sharing executive.
As a result, Mr Taylor said he had still not made up his mind whether to back his leader, Mr David Trimble.
At the same time, Sinn Fein's Mr Martin McGuinness delivered a potential hammer blow to Mr Trimble by asserting that "there is no default mechanism in the Good Friday agreement" and that the scenario presented by Mr Mandelson yesterday fell outside its terms.
Mr Mandelson told MPs that "default" could arise in respect of devolution as well as decommissioning, but, he said: "If there is default, either in implementing decommissioning, or indeed for that matter devolution, it is understood that the two governments, British and Irish, will take the steps necessary to cease immediately the operation of the institutions - the executive, the assembly, the North-South ministerial council, the British-Irish council, the civic forum and the North-South implementation bodies."
During Commons exchanges, Mr Trimble told Mr Mandelson: "Without decommissioning devolution will not survive, if only because our position would become unsustainable, to which I would add, we would not wish to remain . . ."
Sinn Fein seemed particularly incensed by Mr Mandelson's indication of what he thought might happen thereafter. The Secretary of State said: "Finally, let me say to them, that those who are embarking on this journey in good faith will not be left on their own. "If all our expectations of the Good Friday agreement are not met, I will be seeking a way forward in co-operation with those committed to the process, based on the principles of this agreement."
British sources indicated that while Mr Mandelson could not commit the SDLP to proceed in the executive without Sinn Fein, a "new dynamic" could arise in the political process in the case of default by the IRA.
A Sinn Fein source demanded: "How come the British government, which has refused to develop a plan B for 16 months while unionists have been in default over devolution, is now prepared to give the unionists a plan B a week before we get the institutions up and running?"
Accusing Mr Mandelson of throwing "a sop to the unionists", the source said: "We have not, would not, will not agree to a failsafe clause in any shape or form . . ."
The Sinn Fein president, Mr Gerry Adams, in a statement last night in response to Mr Trimble, said that decommissioning was only possible on a voluntary basis but that it was "an essential part of the peace process".
He added "There is no hidden agenda. Sinn Fein's public position is our private position. Our party wants to see the full implementation of the Good Friday agreement."
Later speaking on UTV's Insight programme, Mr Trimble described Mr Adams' statement as "significant" and said that while there had been conflicting messages from the republican movement over the weekend, he was confident Sinn Fein would honour its obligations.
Speaking on the same programme, Mr Jeffrey Donaldson MP said while he would be voting against the deal on Saturday as the IRA had nor done enough, the vote would not be turned into a leadership issue.