At Dublin Castle and later in Government Buildings yesterday the North's First Minister, David Trimble, was struggling for his political survival, looking to the Taoiseach, Mr Ahern, to provide him with a lifeline.

Pro-Belfast Agreement unionists are suffering a crisis of confidence in the agreement, Mr Trimble told the Taoiseach. What could he do to help restore that confidence?

Patten, republican dissident violence, loyalist feuding, demilitarisation, and the absence of a further IRA move on arms were pushing moderate unionists into the No camp.

Look at the result from South Antrim, if you don't believe me, was Mr Trimble's message. He primarily wanted the Taoiseach to put the squeeze on Gerry Adams and Seamus Mallon to provide some space and comfort for Yes unionists.

Mr Ahern is stuck between two options: to throw Mr Trimble a political lifebelt if that is at all possible, or to accept the opinion of some in Government circles, the SDLP and Sinn Fein that there's no point in attempting a rescue because Mr Trimble is sunk anyway.

"If David Trimble goes down the whole agreement is banjaxed" was the warning from one of the Ulster Unionist Party leader's most trusted lieutenants.

Sinn Fein was unimpressed. The North's Education Minister, Martin McGuinness, was blunt before yesterday's meeting of the North-South Ministerial Council at Dublin Castle.

"It is absolutely vital and essential that the Good Friday agreement is implemented as agreed. That is more important than the fortunes of any individual," said Mr McGuinness, echoing the comments of the Sinn Fein president, Mr Adams, on Monday.

Mr Mallon has similarly spoken, saying the Belfast Agreement is bigger than either him or the First Minister.

So we were back to crisis mode, although Mr Ahern portrayed this latest assault on the edifice of the Belfast Agreement as an obstacle, not a major difficulty. However, if there appeared some initial complacency in Dublin about the fallout from William McCrea's victory in South Antrim, it has been replaced by cold reality.

"I think the penny has dropped with the Irish Government," said a Trimble aide.

The senior Trimbleite was very forthcoming with the press. He sketched out what pro-agreement unionists fear will happen in the next few weeks. No-unionists will "make life difficult" for Mr Trimble at the Ulster Unionist Party annual conference on Saturday week. It is expected to be a rumbustious affair.

Within two weeks of the conference, they will call a meeting of the 860-member ruling Ulster Unionist Council with the intention of scuppering Mr Trimble and opening the way for Jeffrey Donaldson to succeed him, he continued.

They would do this by means of a direct challenge or a policy motion tying Mr Trimble to an impossible position on IRA arms or policing, thus making his continuing leadership untenable.

"The reality is that David Trimble is the linchpin holding the agreement together," added the Trimble supporter. "He is central to unionist confidence in the agreement. If you lost David Trimble how do you stop the agreement going totally into reverse?"

The Trimble confidant argued that of all the problems besetting the Ulster Unionists, policing was the major hurdle. One possible means of buying time for Mr Trimble would be to put the Belfast Agreement into review; an "appalling vista" which Dublin, the SDLP and Sinn Fein don't even want to contemplate.

It brought one wry comment yesterday when a journalist suggested that if George Mitchell was out of town perhaps a newly-unemployed Bill Clinton might be willing to chair such a review.

This overall gloomy unionist analysis earned little sympathy from Sinn Fein or the SDLP. Their response was generally along the line of the famous quote from Mandy Rice-Davies: "He would say that, wouldn't he?"

SOME nationalist and republican politicians argue that Mr Trimble's problems are of his own making, that he failed to sell the elements of the agreement which are positive for unionists, such as the removal of Articles 2 and 3 and republicans accepting that there cannot be a united Ireland without the consent of a majority of the people of Northern Ireland.

Sinn Fein and the SDLP are insisting that Patten must be implemented in full. Any dilution of its proposals, even if that could save Mr Trimble, would be pointless because without Patten nationalists just wouldn't join the new police service, and the parties certainly wouldn't encourage them to do so. Without nationalists signing up to a new policing system, where was the new political dispensation?

It was curious that while the Trimble briefer was concentrating on Patten at Dublin Castle yesterday morning, when the First Minister and the Taoiseach met at Government Buildings in the afternoon they were working to a wider brief. Mr Trimble and his team dealt with the broad range of unionist concerns, from the release of prisoners, the fears about scaling down the British army presence when republican dissidents are so active to the UDA-UVF feud to policing.

Mr Trimble appeared more relaxed after the meeting. The body language between himself and Mr Ahern seemed positive. "Bertie has that effect on David," said one observer.

A senior member of the UUP team described the meeting as "good". A high-ranking member of the Taoiseach's squad said: "It was a positive meeting . . . All is not lost."

It was hard to find good reason for the palpable switch in mood between morning and evening, but the First Minister found some reassurance from his discussions with the Taoiseach. There is no doubting that Mr Trimble is not bluffing about his difficulties.

It seems the onus is now falling on Mr Ahern to act as a lobbyist for Mr Trimble with Sinn Fein and the SDLP. His role probably will be to establish if there is any room to manoeuvre on policing, and to ask Mr Adams if he could see his way to persuading the IRA to open up further arms dumps for inspection.

There was no positive answer to these questions last night, but at least Mr Trimble concluded his press conference by saying he was determined to "see a way through" the current difficulties.

Setting a major challenge for all the pro-agreement parties, Mr Trimble said: "It is not beyond the wit of man [to find a solution]."