The Taoiseach and the British Prime Minister will begin trying to sell their blueprint to save the Belfast Agreement to the pro-agreement parties later this week after finalising the package yesterday.
The measures agreed include new concessions to nationalists on policing designed to bring an unconditional IRA commitment to put its weapons beyond use.
Mr Ahern, on an official visit to Argentina, spoke by phone to Mr Blair for 20 minutes yesterday to finalise the package on the four outstanding issues: police reform, the reduction of the British military presence, putting paramilitary weapons beyond use, and ensuring the new political institutions in the North remain stable.
Mr Ahern confirmed yesterday that the package "is now agreed between us" and that now "the stakes couldn't be much higher".
The two governments were discussing until the last minute a proposal to introduce a form of positive discrimination in favour of middle-ranking or senior gardai applying for equivalent posts in the new Northern Ireland Police Service. The proposal is aimed at increasing Catholic representation at higher levels in the force. It is not yet known whether the proposal is in the final package.
There were also last-minute discussions on the Sinn Fein demand that former paramilitary prisoners not be disqualified from serving on local policing boards.
Senior sources who have seen the final package said last night they did not expect all the parties to sign up to everything in the deal. They accept the UUP will be unhappy with some of the concessions on policing. However, they hope unionists will sign up to the further police reforms, on the basis that there is a significant shift on offer on the arms issue.
The package aims to remove the conditions the IRA attached to decommissioning in its statement of May 6th, 2000. The IRA then said it would begin putting weapons beyond use only in the context of the full implementation of the other aspects of the Belfast Agreement.
The two governments hope the new package of police reforms and of demilitarisation - including the reduction of the British military presence in south Armagh - will lead to such unequivocal IRA commitment. Details of how weapons will be put beyond use are expected to be left for discussion between the IRA and the Independent Commission on Decommissioning.
The Northern Secretary, Dr John Reid, said recruits to the Police Service of Northern Ireland would not be trained in the use of plastic bullets, at least for two years. The governments hope this compromise might go some way towards persuading Sinn Fein not to campaign against young nationalists joining the police.
The package will also provide for an amnesty for republican and loyalist paramilitaries "on the run", according to Northern sources, and will propose that an international judge decide on the merits of holding inquiries into the killings of Mr Pat Finucane, Ms Rosemary Nelson and Mr Robert Hamill. And as a counterweight to satisfy unionists the judge would also decide on the merits of investigating claims that there was Garda collusion with the IRA in the killings of Lord Justice Maurice Gibson and his wife Cecily in 1987, and with the IRA killings of RUC Chief Supt Harry Breen and Supt Bob Buchanan in 1989.
Analysis: page 7