The British Prime Minister, Mr Tony Blair, and the Taoiseach, Mr Ahern, are today giving "one final push" to the Leeds Castle negotiations in an effort to break the political stalemate in Northern Ireland.
In a significant restatement of their joint intent the Taoiseach yesterday again endorsed Mr Blair's determination that the conclusion of the talks this afternoon must mark the point of decision about the future direction of the political process.
There were strong indications yesterday of a real and growing engagement by Sinn Féin and the Democratic Unionist Party with the range of issues and package of measures which would be necessary to the successful restoration of a power-sharing administration at Stormont.
However, in language similar to that used by her Downing Street opposite number 24 hours before, the Taoiseach's spokeswoman insisted that today's 7.30 a.m. start would mark "the final contribution" by Mr Ahern and Mr Blair to this particular negotiation.
"These things have to have a beginning and an end," the spokeswoman said.
"They are giving it their all, and we should know \."
Yet as senior DUP figures last night anticipated a positive outcome to the talks, but with "more process" to come, a leading member of the Sinn Féin delegation dismissed the attempt by Mr Blair and Mr Ahern to impose a deadline as "nonsense".
Mr Pat Doherty MP said: "As for this nonsense that politics will come to an end on Saturday afternoon, that is what it is - nonsense."
The Taoiseach's spokeswoman indicated that she did not know what the alternative way forward might be, and that any consideration of a Plan B would be for after the conclusion of the Leeds Castle negotiation.
Ulster Unionist and Progressive Unionist Party sources confirmed their understanding, however, that Mr Blair was determined either to secure an agreement between the DUP and Sinn Féin or, alternatively, to present what he and Mr Ahern would consider acceptable and dare the parties to reject it in a vote in the Stormont Assembly.
The Prime Minister has also reportedly used strong language to underline his frustration with the continuing political impasse.
He and the Taoiseach are understood to have indicated to the Rev Ian Paisley and his colleagues early yesterday language of the kind they believe republicans are prepared to use in respect of proposed acts of paramilitary completion and the end of the Provisional IRA as a paramilitary organisation.
However, by late evening DUP sources said this had not been reduced to paper and they were in any event declaring themselves doubtful if, when it appeared, it would contain the specifics, timetables and deadlines which Dr Paisley has said he would require.
Dr Paisley's deputy, Mr Peter Robinson, has reportedly said that what he understands to be on offer from republicans - although well short of the DUP's requirements - would of itself represent a better deal on the arms issue than anything previously achieved by the Ulster Unionist leader, Mr David Trimble.
However, during an early appearance before the cameras alongside Mr Ian Paisley jnr, Mr Robinson cautioned that talk of being "on the cusp of getting agreement" did not reflect the position at that point inside Leeds Castle.
It is understood that the DUP was coming under strong pressure from the two governments and the other parties over its attempt to renegotiate aspects of the Belfast Agreement.