The Taoiseach, Mr Ahern, and the British Prime Minister, Mr Blair, may travel back to Belfast next Thursday. And on the other hand, they may not.
In both capitals last night the operative assumption remained that the two leaders would rejoin the resumed negotiations with the pro-Agreement parties, adjourned on April Fool's Day with the Hillsborough declaration. But their precise travel plans remained highly contingent - reflecting the mood of uncertainty which precedes the resumption of the talks on Tuesday.
Little real work appears to have been done this post-Easter week. And while the Taoiseach is expected to resume contact with Mr Adams over the weekend, Sinn Fein sources last night said they still knew nothing of the proposed structure, format or agenda for the second leg of the negotiation, designed to resolve the decommissioning impasse and permit the establishment of the executive and other institutions prescribed by the agreement.
In the first instance it appears that the Minister for Foreign Affairs, Mr Andrews, and the Secretary of State, Dr Mowlam, will lead their delegations into a series of bilateral and multilateral discussions - with Mr Ahern and Mr Blair making a final decision on whether to resume their personal effort in the light of progress.
Some sources close to the Taoiseach are cautiously optimistic that breakthrough will be achieved, while questioning if it can be done within the week. Others doggedly insist a result can be delivered by next Friday, while admitting they will not know Sinn Fein's actual position until they are seated across the table.
Senior Sinn Fein sources, meanwhile, insist that neither camp has grounds for confidence - in either the short or medium term - if the Hillsborough Declaration remains the basis of their expectation.
British and Irish officials have parsed and analysed the series of Sinn Fein pronouncements since last Sunday, culminating in Thursday's assertion by the party's officer board that the draft declaration "is an unacceptable departure from the commitments given on Good Friday 1998". amounting to "a massive change" in the terms of the Agreement.
And there is no evident disparity between Sinn Fein's public and private line. While conscious of the Good Friday precedent, and wise never to say "never", one senior party source last night insisted he could not see progress being made on the basis of the Hillsborough draft. Its decommissioning proposals, he maintained, were "a precondition dressed up as something else" - a "unilateral demand" by the two governments, which the leadership had made plain it could not deliver.
On March 31st the Taoiseach asserted that the "principles" had been established, leaving only questions of dates and sequencing. But Sinn Fein, the source said, did not accept the notion of an "obligation" - either on the IRA to deliver a start to decommissioning in order to get Sinn Fein into the executive, or on Sinn Fein to have delivered total disarmament by May 2000.
The only obligation, he asserted, was for the party to use its influence toward the goal of decommissioning within the context of the successful implementation of the agreement. And they would be returning to next week's talks insisting that both governments "get back to basics" and restore "the primacy of the agreement" after "a year of broken promises and missed deadlines".
Insisting that the issue of weapons remained "fundamental and theological", he said republicans were "increasingly exasperated and angry" at the perceived willingness of London and Dublin to bow to a still exclusionist unionist agenda. And Mr Trimble, he ventured, had only appeared to accept the Hillsborough declaration once clear that Sinn Fein was set to reject it - a tactical manoeuvre in the continuing game of blame allocation.
That said, the two governments had backed Mr Trimble's interpretation of the agreement's requirements in respect of decommissioning - albeit by way of seeking to translate his "precondition" into a "voluntary obligation". Was it conceivable they would now perform an about-turn? And what would happen to Mr Trimble if they did?
Reflecting a belligerent line not heard for many months, the Sinn Fein source replied: "If David Trimble can't deliver the unionists, he is of no value to the peace process . . . and the unionists will have to look for a new leader."
It is at this sort of rhetorical point that government sources begin to display impatience, and the belief that the underlying Sinn Fein position is something other than stated.
The Taoiseach and his closest advisers are convinced Mr Trimble wants the agreement to work, and to establish the executive with Sinn Fein aboard. There is, in any event, no other option. Sinn Fein may be convinced that at least some senior members of Mr Trimble's party still hanker after an agreement with the SDLP to proceed without them. But neither the SDLP nor the Government will play.
The Government's position remains as defined by the Taoiseach in his Sunday Times interview: that if there is going to be a new government in the North it must be fully inclusive, but that it won't happen if Mr Trimble walks for want of some agreement on decommissioning.
Moreover, after the pre-Easter negotiations at Hillsborough and the apparent commencement of a serious engagement between the UUP and Sinn Fein, the Dublin Government appears convinced of two other things: first, that each side understands the vulnerability of the other; second, that neither side wants out of the process.
Some senior SDLP members accept (happily enough) that the Hillsborough draft does represent (at least "in a technical sense", as one puts it) a rewriting of the Belfast Agreement. But that is not accepted in Dublin.
While the agreement is "base camp", it is observed that it has required amplification and further negotiation on a range of issues - most particularly, over two long negotiations, to achieve agreement on the detail of the cross-Border Implementation Bodies.
Likewise, decommissioning is seen as a classic example of a problem postponed, but clearly demanding further negotiation and resolution. Countering Sinn Fein complaints, one insider notes that the agreement emphatically did not say there would be no decommissioning.
Rather like the IRA, he says, "it never went away" and clearly requires resolution now if the whole enterprise is to take off. Bowing to the reality that nobody can force the IRA to decommission, he accepts, likewise, that "nobody can force David Trimble to join an executive with Sinn Fein" without it.
So - for all the harsh words and the clear irritation with Mr Ahern (and Mr Blair) - there appears cautious confidence that a way forward can yet be forged.
It is rooted in many things: the knowledge that the republican movement has more than once been prepared to think the seemingly unthinkable; the conviction that the Sinn Fein leadership retains belief in the capacity of the agreement to deliver profound political and constitutional change; the knowledge that a willingness to see the agreement fall could open the North to "events" which the republican movement might not be able to control; and, crucially, for all the post-Hillsborough focus, the view that the Ahern/Blair declaration has not reduced everything down to a single issue.
This could be the point of danger for Mr Trimble. For if the sense at Hillsborough was of Sinn Fein feeling (and looking) pained and isolated, the logic of this process would suggest a pendulum, to some extent, swinging back. In the same spirit mentioned above, the two governments will be obliged to respond to Sinn Fein's demands for amplification and clarification. And if Mr Adams wants to move, the missing detail on two key issues might be provided as encouragement.
The declaration was deliberately vague as to the precise timing of the transfer of powers in relation to the proposed collective act of reconciliation (requiring loyalists as well as republicans to put some weapons beyond use).
Moreover, the British have apparently not yet revealed (certainly to Mr Trimble) the detail of their long and eagerly-awaited paper on the "normalisation" of security arrangements.
Could specificity about timing yet enable a "voluntary" act by republicans "simultaneously" with the creation of the executive, and in the context of a collective act of demilitarisation as envisaged by the agreement? And would that suffice for Mr Trimble? Nobody knows. But two things can be said for certain.
If the Hillsborough draft testified to the devilishly clever nature of Anglo-Irish diplomacy, the draftsmen will be back at their work next week. And if the Ulster Unionists looked (and felt) relaxed on April 1st, Mr Trimble will know that he and they face a few sleepless nights yet.