The Taoiseach expressed the belief in Washington yesterday that the establishment of a powersharing executive in the North on March 26th was now a fait accompli.
After a meeting with the Democratic presidential contender, Senator Hillary Clinton, Mr Ahern said the March 26th deadline had been set and there was no reason for it not to be met.
"Everything along the way, every single demand, every single issue that has been put on the table has been delivered. There is only one thing left: powersharing."
In the light of all that had been done, there was no reason for the institutions not to be set up, he said. "In the absence of anything else on the agenda - and I don't think there is anything else on the agenda - my view is that the 26th is a fait accompli."
He publicly thanked Senator Clinton and her husband, former president Bill Clinton, for all the support they had given to the search for a solution in Ireland.
Senator Clinton joked that she "would like to go back to Belfast as president and bring my husband with me".
Later the Taoiseach attended a lunch hosted by the speaker of the House of Representatives, Nancy Pelosi, which was also attended by President Bush.
Mr Ahern, who expressed pride that it was his 10th consecutive opportunity to attend the St Patrick's Day festivities in Washington as Taoiseach, said he was honoured by the presence of the president and looked forward to meeting him in the White House today. "Politics, whether in Washington or Ireland, is truly the art of the possible. What once seemed impossible in Northern Ireland not very long ago now is within reach," said Mr Ahern.
He said the people of the North had voted to see the institutions of the Good Friday agreement restored and they wanted the parties to work together in a shared government on their behalf.
"The IRA campaign has ended, the weapons have been decommissioned, inclusive support for policing has been agreed and the programme of normalisation of security in Northern Ireland will be completed shortly," he said.
"A great deal of valuable time has been lost since the Good Friday agreement was signed in 1998 but the restoration later this month of an inclusive powersharing executive gives real hope and represents an opportunity of historic proportions.
"Prime Minister Blair and I will spare no effort to secure the restoration of the institutions of shared government," he said.
The Taoiseach added, however, that time was pressing and it would be unconscionable if this opportunity of a generation was to falter at this final moment.
He welcomed American support for peace and also on individual issues like the need for a full public inquiry into the murder of Belfast solicitor Pat Finucane.
Sinn Féin's deputy first minister designate, Martin McGuinness, who is also in Washington, said his party was determined that the deadline would be met.
"I think as time has moved on that Ian Paisley himself has come to realise that there really isn't much point in allowing that date to slip," he said at a breakfast.
"I think that all of the mood music in the course of the last week or so has been good and I think that there is increasing optimism and hope that powersharing and all-Ireland institutions will be in place by the 26th of March. And if that happens, then obviously everybody has crossed the Rubicon."
Mr McGuinness said both Sinn Féin and the DUP strongly believed in the need for a peace dividend to underpin a new executive.
"I think that Ian Paisley's support for our argument is very welcome and he has been arguing in the context of the last number of weeks that this is a precondition. He's been involved in a number of meetings over the last number of days, as has Gerry Adams, with both Tony Blair and Gordon Brown. I myself spoke to Gordon Brown before I left for the US. And I think that people are conscious of the arguments but I still think that the date of the 26th is sacrosanct and it's a date that we all have to meet," he said.