The North's First Minister, Mr David Trimble, has urged paramilitary groups to grasp the "historic opportunity" to implement the Belfast Agreement in its entirety by decommissioning weapons.
Speaking yesterday after a morning meeting with Sinn Fein representatives, the Ulster Unionist Party leader said he was anxious to see "whether there is any willingness on the part of the paramilitary-related parties to start to carry out their commitment to the agreement".
The dismantling of paramilitary organisations was not just an issue for Sinn Fein but for the Progressive Unionist Party and the Ulster Democratic Party also, he added.
"The question for today is whether the paramilitary-related parties have the will to grasp this historic opportunity to implement this agreement in its entirety."
Surrounded by up to 20 UUP Assembly members, Mr Trimble said his party had done all that was required of it under the Belfast Agreement.
The choice lay with those who had yet to carry out their side of the bargain, he added.
The British Prime Minister, Mr Tony Blair, and the Taoiseach, Mr Ahern, met leaders of a number of political parties at Stormont in the early part of yesterday before leaving Belfast for Hillsborough Castle.
After meeting the two leaders, Ms Monica McWilliams of the Women's Coalition said it was apparent the mood had changed.
"Parties have now become focused on getting a solution," she said. There was a need to offer guarantees of good faith.
The Alliance party leader, Mr Sean Neeson, said there was a feeling of genuine engagement by all sides to resolve the decommissioning row.
"I still believe there is a 50-50 chance of agreement being reached," he added.
"There was a sense that this is very much D-Day, and while the two main protagonists in this dispute are the Ulster Unionists and Sinn Fein, every pro-agreement party is working collectively to achieve a breakthrough. But in the end it really is a question of will," Mr Neeson added.
Mr David Ervine of the Progressive Unionist Party said that "potentially there may be a way around this".
However, he stressed that both the UUP and Sinn Fein had "trapped" themselves in their intractable positions.
Mr Breandan MacCionnaith and Mr Gerard Rice, representatives of nationalist residents' groups in Portadown and Belfast respectively, were heckled by anti-agreement unionists when they spoke to reporters after meeting Mr Blair and Mr Ahern.
Mr MacCionnaith said they had highlighted the need to ensure that Catholics in Portadown could live free from sectarian harassment.
He claimed 160 demonstrations by the Orange Order and other loyal orders were planned for Portadown in the run-up to July.
The Orange Order was attempting to mobilise 70,000 members on July 12th if they were not allowed to march down the Garvaghy Road, he added.
They said they had raised the need for an independent inquiry into the murder of the human rights solicitor Ms Rosemary Nelson, and another inquiry into the death of the Catholic father of two Mr Robert Hamill, who was killed by loyalists in Portadown two years ago.
Speaking after his party's meeting with Mr Blair and Mr Ahern, the deputy leader of the Democratic Unionist Party, Mr Peter Robinson, said any deal that involved "guns in the future" would not wash with the unionist people no matter what guarantees were offered.
Mr Cedric Wilson, of the anti-agreement Northern Ireland Unionist Party, said Mr Blair had reiterated his credentials as a unionist to his party's delegation.
"He was in talkative mood," added Mr Wilson, who had earlier challenged Mr Blair on his arrival at Parliament Buildings.
The spokesman for the Ulster Democratic Party, Mr Gary McMichael, said he had stressed to the leaders that any resolution reached on decommissioning must not play into the hands of anti-agreement unionists by weakening the position of unionists attempting to work the Belfast Agreement.