The fate of the Stormont multiparty talks hangs on today's meeting between Mr Tony Blair and the Ulster Unionist leader, Mr David Trimble. Mr Trimble faces internal party revolt combined with public denunciation from smaller unionist parties if he votes for the joint Anglo-Irish decommissioning document on Wednesday.
Senior Ulster Unionist sources were not ruling out the possibility, however unlikely, that Mr Blair could provide guarantees and assurances that would make it possible for Mr Trimble and his party to remain in the talks.
Mr Blair would have to make it clear, as he did in his Belfast speech last May, that the limits of any settlement would be defined by the wish of the Northern Ireland majority to remain part of the United Kingdom.
He would also have to give clear guidelines for judging the quality of the IRA ceasefire and to specify whether "punishment beatings" and targeting were included.
There is particular concern among senior unionists about targeting - following people, building up intelligence on their movements in the home and work environment and, in some cases, making "mock-shooting" signs at them. There has been targeting of nationalists and republicans also.
"It's terrorism without people being killed," senior unionist sources said. They did not trust the republican movement and believed targeting and acts of violence carried out under other names would be used to intimidate unionist representatives in any talks process.
Observers expect Mr Blair to point to Gen John de Chastelain, one of the three chairmen of the multi-party talks, as the obvious person to take charge of verifying the decommissioning of paramilitary weapons. Mr Blair is expected to reiterate that every effort will be made to secure a handover of such weapons and to give an undertaking that the committee to liaise between the parties in the talks and the verification commission will be functioning by the end of August.
The mood at senior unionist level is bleak and augurs badly for the continuation of the talks process in its present form. Party sources said the elements that voted Mr Trimble into the leadership were the least likely to support a compromise. "We have learnt lessons from the case of Brian Faulkner," Ulster Unionist sources said.
Reports that the ceasefire was "tactical" and would last only four months, though dismissed angrily by Sinn Fein, have increased the sense of unionist alarm. At the same time there is a reluctance to abandon the talks process because this could open the way to having a settlement imposed upon the North.
If the unionists walk out of the talks, Northern Ireland would then be facing a situation where the nationalist parties were congregating at Stormont and the unionists were gathered at the Northern Ireland Forum. In that "dual power" situation, the two governments would have to set up a channel of communication and a "proximity talks" format has been suggested as a possibility.
There are reports that a US delegation, similar to the one which visited the North before the 1994 ceasefire, may come to Belfast this week to meet the various party leaders.
SDLP sources said they believed the door was now open to negotiating a settlement but that they were also conscious of the current sensitivities of unionists.
They stressed rapid movement was required to fill the North's political vacuum. Whatever about the hurt feelings of unionist leaders, mainstream unionist voters did not want to see another 17 months of inaction such as followed the last IRA ceasefire.
Nationalist sources in the peace process said the good relationship between Mr Blair and the Taoiseach, Mr Ahern, had been crucial to the latest developments.
Sinn Fein speakers have stressed the need for movement on the prisoners issue and this is expected to come in the near future with further transfers from English jails to prisons in Northern Ireland or the Republic.
Republican sources said they believed the logic of Mr David Trimble's position suggested he should stay in the talks but they were not sure this would be feasible politically for him at this stage.
The Northern Ireland Secretary, Dr Mo Mowlam, last night reasured unionists that the government was not giving up the decommissioning of weapons.In an interview with the Mirror she said: "We haven't given up on decommissioning of weapons at all. The government believes decommissioning should take place alongside the all-party talks and as trust is built it will become easier".Admitting she was tired after the recent developments, she spoke for her reaction to the announcement of a new IRA ceasefire. I was very pleased and delighted with the restoration of the ceasefire. But I have a sense that the real hard work starts for me now."We must make sure the unionists stay in the process and the IRA show in words and deeds that the ceasefire in genuine".