The SDLP has raised the stakes and dramatically thrown the spotlight back on the Strand One negotiations before tonight's crucial summit between Mr Ahern and Mr Blair in London.
The party leader, Mr John Hume, and his deputy, Mr Seamus Mallon, last night confirmed their desire to see an executive or cabinet head a new Northern Ireland assembly, and repeated their strong opposition to unionist proposals for a committee-led administration in the North.
Speaking outside 10 Downing Street after more than 75 minutes of discussions with the British Prime Minister, Mr Hume told reporters: "We would think it's in the interests of the people of Northern Ireland that, if there is going to be an assembly, there should also be a government."
Speaking in Belfast, Mr Mallon rejected any attempt to establish what he described as a Belfast City Council-type administration, and insisted the new assembly would have to have legislative as well as administrative powers.
The SDLP salvo came as the Taoiseach prepared to try to persuade the British government to back its plans for a powerful North-South council, with executive powers, rooted in legislation to be passed by the Dail and the House of Commons.
While there are indications that some senior Ulster Unionists are prepared to consider the creation of a power-sharing executive in the North, the expectation is that such a "concession" would be coupled with an entrenchment of the party's opposition to a free-standing North-South Council.
Indicating the scale of the gulf to be bridged, Mr Mallon said of the proposed assembly: "It has to be a body with the power of decision and the power to legislate, and play a full and meaningful role in the North-South council of ministers where executive powers would also be exercised."
Although he never used the words "optimistic" or "pessimistic", Mr Hume said he was "hopeful" an agreement would be reached by the April 9th deadline.
He said: "What strengthens my hope is my knowledge and experience that tells me that the vast majority of the people from both sections of our community want to see an agreement, and an agreement that produces new thinking based on respect for the identities of both sections of our people."
Mr Hume praised Mr Blair for raising the Northern issue to the top of his government's priorities and said they had had "a very good meeting . . . a very intensive discussion of the current situation."