Inside the UUP: Some senior pro-Agreement unionists are suggesting that Mr David Trimble could use changed electoral rules to prevent party dissidents contesting fresh Assembly elections under the Ulster Unionist banner.
This was confirmed last night amid a growing sense in unionist circles that Mr Trimble believes "on balance" that an agreement can be reached on acts of IRA and British "completion", paving the way for the return of devolved government in Northern Ireland.
One key insider suggested "a better than 50 per cent chance" of a breakthrough in the negotiations on the draft British-Irish agreement, designed to secure the cessation of the IRA as an active paramilitary force and the full implementation of all remaining aspects of the Belfast Agreement.
Leading hardliners are predicting that any move to restore devolution could trigger a rerun of the 1973 UUP experience, when the Brian Faulkner-led party split over the Sunningdale Agreement, and UUP standard-bearers fought each other as "pledged" and "unpledged" candidates in the subsequent election.
However, changes in UK rules for the conduct of elections could empower Mr Trimble to prevent such a scenario. Like all parties, the UUP, with its description and logo, is registered with the Electoral Commission. Mr Trimble is also registered as his party's "nominating officer" for elections.
Confirming that this power could be used to prevent dissidents standing under the UUP label in defiance of majority party backing for any deal, one senior unionist source said last night: "If I was the nominating officer, I would write to all the selected candidates seeking their commitment to the party's programme. If they failed to agree, I would refuse to nominate them."
Acknowledging the risks to Mr Trimble should he ever deploy this "nuclear option", advocates of this course admit it could lead to a formal split in the UUP. At the same time, both sides seem to accept that any "acts of completion" deal is likely to produce a final and defining battle for "the soul" of the party.
Anticipating his opponents, Mr Trimble told delegates on Saturday that he would put any deal to an emergency meeting of the ruling Ulster Unionist Council.
Party sources confirmed such a meeting could take place as early as Saturday week. However, they added that any such development would depend on "the substance and convincing nature" of an IRA offer.
As the British Prime Minister, Mr Tony Blair, and the Taoiseach, Mr Ahern, prepared to fly in for today's crucial summit, Mr Trimble was still insisting that any IRA weapons decommissioning must be publicly visible, while any statement from the republican movement must confirm that its "war" is over.
While suggesting they have "in principle" agreement, the unionists are apparently still awaiting detailed proposals for an independent element in the monitoring of paramilitary ceasefires and "sanctions" to be deployed against a party deemed in breach of its commitment to exclusively peaceful and democratic means.
Official sources said it was proving difficult to square the circle between these demands and the seemingly implacable opposition of Sinn Féin.
Significantly, while Sinn Féin leaders and other key republicans negotiated with British and Irish officials in London over the weekend, a major point of discussion within the Trimble camp was the speed with which the party could contemplate a return to the power-sharing Executive.
If the negotiations prove successful, the British government's preferred option would be to lift the suspension of the Stormont Assembly and have ministers reinstated ahead of prorogation, due on March 21st.
Ministers would remain in office until the elections scheduled for May 1st. Some Trimble supporters fear this would not give him time to "sell" any deal and are urging him to seek a postponement of the elections by up to six months.
Under the third option being urgently considered, Mr Trimble and fellow ministers would not resume office ahead of the election but would regard the election as an effective "referendum" on any deal, in which they would seek a fresh mandate to resume power-sharing.