Mr Seamus Mallon said the current difficulties over Mr David Trimble's North-South Ministerial Council ban on Sinn Fein and the persistent problems on decommissioning could be resolved if the Ulster Unionists, Sinn Fein and the IRA shifted their positions.
Last night he called on the IRA to re-engage with Gen de Chastelain's decommissioning body and for the Ulster Unionist Party to end its policy of disrupting the agreement and instead put trust in the two governments.
Mr Mallon also reserved judgment on whether the SDLP would accept Mr Peter Mandelson's police reform proposals until he sees the final shape of the Police (Northern Ireland) Bill, which is due to be completed at Westminster on Tuesday.
He told the 30th annual conference of the SDLP in Newcastle, Co Down, last night that a possible means of overcoming the recurring political crises over decommissioning would be for Dublin and London to establish the adequacy of measures to put paramilitary weapons beyond use.
"At Hillsborough there was a commitment by the IRA to reengage with the de Chastelain Commission. That re-engagement should take place now. It should be meaningful and sustained. It should not be a bargaining chip," said the Deputy First Minister and SDLP deputy leader.
"Progress with decommissioning should be closely monitored and its adequacy judged by the two governments. Not by Jeffrey Donaldson, not by Martin McGuinness, not by Seamus Mallon. By the two governments," he added.
"For their part the UUP should make a commitment to stop disrupting the institutions established by the agreement. Many suspect - and not without reason - that even if there is immediate re-engagement there will be further Ulster Unionist Council meetings in January and again in March which will ratchet up demands and threaten the institutions once again.
"The two governments should set their faces against any more unilateral tampering with institutions owned by no one political party, no one political persuasion, but by the people of Ireland, North and South.
"If these two commitments came together then the work of the institutions could proceed. We would not be limping along distracted by the next Ulster Unionist Council or trying to interpret the latest decommissioning moves. Enough space might be created to allow real progress on decommissioning, to allow the work of the institutions to flourish and for trust to grow."
He repeated that the Northern Secretary had the power to intervene and insist that Sinn Fein Ministers be allowed attend NSMC meetings.
Mr Mallon will not reveal the SDLP hand on the Police Bill until it is finalised. "Next week the Police Bill reaches its conclusion. And we must consider ours. We must consider whether we have the new beginning to policing promised by the Patten report," he said.
"Let me be clear: we are ready and willing to work this, if it is workable."
Mr Mallon said that the SDLP, as its "architects" and "guardians", must defend the Belfast Agreement. He accused the "forces of reactionary unionism and of violent republicanism" of seeking to undermine the agreement and said that even supposedly pro-agreement unionists were failing to defend the accord.
Referring to the UUP's decision to select an anti-agreement MLA, Mr Peter Weir, for the general election in North Down, Mr Mallon said: "No wonder then that unionist supporters of the agreement have grown confused and discouraged, feel disenfranchised."
He said that the SDLP respected and valued the unionist identity and values. Pro-agreement unionists, however, should defend the agreement. "We hope you will not lose faith", Mr Mallon said, adding: "But you have to make your voices heard."
He said the SDLP would continue to resist the anti-agreement challenge. "To the political tradition which brought us `no surrender', then `no agreement', let me suggest another slogan: `No, Jeffrey, no, thanks'."
To republicans he said: "Surely by now you must realise that it is time to let go - finally, once and for all - of any association with violence as a means of advancing a political position, the retention of arms and explosives, the continuation of beatings, shootings and killings.
"The failure to do so - cleanly and clearly - has been and remains a major obstacle to the full implementation of the agreement, and the failure to condemn violence - for example, in Fermanagh last weekend - undermines confidence throughout the community."
Read the full text of Seamus Mallon's speech on The Irish Times website at www.ireland.com
