The deputy leader of the Ulster Unionist Party, Mr John Taylor, has warned that the new deal on IRA weapons to allow the restoration of the Northern Ireland Executive could "unscramble" unless the policing issue is resolved to the party's satisfaction.
The new Northern Ireland policing Bill, incorporating the controversial Patten proposals, is due to be unveiled in the next few days.
Earlier yesterday, Mr Taylor had predicted victory for UUP leader Mr David Trimble at the Ulster Unionist Council on Saturday week.
However, he told The Irish Times "that all depends on things being clarified" over the coming days. He added: "If it doesn't work out on policing, this whole thing will more than likely unscramble."
There have been some reports that agreement has already been reached on a change to the Bill implementing the Patten commission's recommendations - expected to be published later this week - which would describe the new Police Service of Northern Ireland as "incorporating" the Royal Ulster Constabulary. However, Mr Taylor appeared to confirm the Irish Government's position on any name change, insisting that, as of now, "there is no deal, absolutely not".
Other party sources indicated that Mr Trimble was expecting a letter from the British Prime Minister, Mr Tony Blair, dealing with policing and a number of other issues, thought to include the British government's attitude to the retention and use of symbols of the British state in the post-agreement era.
In Dublin, the Taoiseach, Mr Ahern, again indicated willingness to consider some measures on the policing proposals but appeared to firmly rule out departure from the Patten proposals.
Despite official denials all round, the belief in political circles is that some "concession" will be announced in an attempt to ease Mr Trimble's task of persuading the UUC to re-enter government with Sinn Fein without IRA decommissioning.
There was little doubt yesterday that, for all the insistence on "clarification" still to come, Mr Trimble's supporters expect him to carry the council by at least the 5743 per cent margin of his victory in the leadership contest in March.
In the Commons yesterday, Mr Peter Mandelson, the Northern Ireland Secretary, made it clear that he expected Mr Trimble to recommend his party's acceptance of the new "putting weapons beyond use" formula.
"For the first time, there is a commitment to put weapons completely and verifiably beyond use, in a context which is realistic rather than simply aspirational," Mr Mandelson told MPs. "There is a more clear-cut assurance of the IRA's peaceful intentions than we have ever heard before."
Mr Mandelson told the House of Commons that the former Finnish president, Mr Martti Ahtisaari, and the former ANC secretary general, Mr Cyril Ramaphosa, who will head the inspections of IRA arms dumps, would arrive in Belfast next Monday.
However, in the Commons the Ulster Unionist leader formally reserved his position, telling Mr Mandelson that irrespective of any decision he took on suspension of the Northern Ireland Executive, "this party will make its own decision".
The UUP appeared rattled last night by the discovery that Mr Mandelson intends to have MPs debate the order lifting suspension on Thursday week, two days before the UUC meeting.