The Taoiseach and the British Prime Minister will decide today whether efforts to break the deadlock in the North should continue next week or be postponed until the autumn.
Mr Ahern and Mr Blair will begin discussions with the key parties starting at 8 a.m. today and will then decide whether a continuation of attempts to restore the North's political institutions is worthwhile.
There were conflicting signals from the two governments and the parties last night as to the prospects of success. However, sources in both governments accepted that unless there were imminent developments, the political process would effectively have to be closed down until the autumn.
Government sources say that, so far, both parties have engaged merely in hypothetical discussions without revealing what they would actually be prepared to do.
Two key elements are required for success. First, there must be an indication from the Ulster Unionist Party that it would participate in a restored Executive if the IRA said its war was over and made clear its intentions about its weapons.
Second, the two leaders will seek an understanding that a clear statement from the IRA on these matters will be forthcoming if the UUP agrees to participate in restored institutions.
Mr Ahern and Mr Blair met the four smaller pro-agreement parties, Alliance, the Women's Coalition, the Progressive Unionist Party and the Ulster Democratic Party, at Hillsborough yesterday evening.
Ms Monica McWilliams, of the Women's Coalition, said she was convinced a political solution would be found but that people should possibly look to the autumn for an ending of the impasse.
Mr Ahern, Mr Blair, Mr Brian Cowen, Mr Peter Mandelson and officials discussed the situation informally over dinner at Hillsborough Castle last night.
The occasion was coloured by the leaking to journalists of an extract from a British government memo which portrayed Mr Cowen as a hardline nationalist who behaved like an "unvarnished" Sinn Fein representative at meetings.
The Government reacted angrily to the leak. The memo maintains that Mr Mandelson believes Mr Cowen to have "no feel for or understanding of unionist concerns". While Mr Mandelson's and Mr Cowen's personal relationship is known to be far from warm, Government sources insisted last night they had "a good working relationship".
Today Mr Ahern and Mr Blair will concentrate on extracting from Sinn Fein and the Ulster Unionist Party their "bottom lines" for these negotiations.
No reliable indicator of the prospects for success could be determined last night. Both Sinn Fein and the Ulster Unionist Party have been writing and rewriting sections of a series of statements that would be issued in advance of the restoration of the political institutions. However, neither has committed itself to a particular formula.
A Government source said last night the process "could take one day, one week, six weeks or six months. What is important is that we establish the bottom line of Sinn Fein and the Ulster Unionist Party".