The Taoiseach, Mr Ahern, and the British Prime Minister, Mr Tony Blair, last night were determined to travel to Belfast tomorrow "deal or no deal", according to senior sources.
They hope the intensive contact that will continue throughout today between the British and Irish governments and DUP and Sinn Féin leaders could still result in a compromise that will allow them sign off on a comprehensive agreement in Belfast tomorrow.
But if these final hours of brinkmanship contacts today between Belfast, Dublin and London end in failure, then Mr Ahern and Mr Blair intend going to Belfast tomorrow to begin the initial process of launching their "Plan B" alternative to the blueprint for agreement.
Often in key negotiations politicians employ inflexible language ahead of making an accommodation with their political opponents.
Although the governments would hope that this was the Rev Ian Paisley's strategy, Dublin and London sources tended to the view that the DUP leader was stating a bottom line position on photographs.
The governments' blueprint to restore the Northern Executive and Assembly is understood to oblige the IRA to allow publication of IRA disarmament after the DUP demonstrates it is sharing power - rather than publication before powersharing, as Dr Paisley requires.
It appeared equally apparent last night that republicans would not agree to this verification demand.
Mr Adams said: "In the next 48 hours we have the opportunity to make a quantum leap forward in the process."
Implicitly stating the republican bottom line on photographs, he said: "Is all of this going to be thrown away because Ian Paisley does not get the process of humiliation he wants?"
Today there is expected to be high-level contact involving all the main players, including Mr Ahern, Mr Blair, Mr Adams, and Dr Paisley, most of it by telephone, as the governments strive for an 11th hour compromise around the issue of visual proof of decommissioning.
If these efforts fail, then, senior sources said, Mr Ahern and Mr Blair would go to Belfast tomorrow "deal or no deal" and publish their proposals, or a summary of them, to try to illustrate to the public that they constituted a fair deal.
This would result in major political recrimination, with the DUP and Sinn Féin seeking to blame the other for the collapse of the attempts to find agreement. Republicans believe that such was the strength of what was on offer from the IRA and Sinn Féin that the DUP would be held chiefly responsible.
Meanwhile, the British government has confirmed in writing that it will underpin a political deal in Northern Ireland with a substantial investment package, Sinn Féin claimed yesterday.
The DUP, which met the Northern Secretary in London yesterday, claimed that it was "leading the way" in the fight for a substantial investment package. Mr Peter Robinson said major government funding was a "key issue".
"If we are to have a new start in Northern Ireland, then we need the wherewithal to have a real impact," he said.
A DUP spokesman said that the "mother of all deals would carry the mother of all prices".
The Sinn Féin chairman, Mr Mitchel McLaughlin, said the terms of the package as outlined to him by the Northern Secretary fell short of what was needed. Mr McLaughlin and the Fermanagh-South Tyrone MP, Ms Michelle Gildernew, met Mr Paul Murphy last week and said they received a written commitment to financially support a political deal.
The party said the Irish Government would also be approached for funding along the Border corridor.