It was April 10th, the day of the Good Friday Agreement, and several senior staff members were gathered around a television set in the West Wing of the White House as the first pictures of the remarkable settlement were being beamed worldwide by CNN.

"I first knew that something historic was about to happen when John Hume hung up on the President," remembers a senior staffer. "He had been called to a very urgent meeting so we knew George Mitchell had obviously gotten a deal. To say we were euphoric would be an understatement."

As they watched the scenes half a world away from Castle Buildings, an uninvolved staffer stopped by to ask what was happening.

"Hell just froze over," said a top Clinton aide emotionally, gesturing at the scenes of old enemies finally making common cause. "There's going to be peace in Ireland."

The euphoria has long since faded at the White House. In its place, however, is a dogged determination to help make the Good Friday Agreement stick. The forthcoming visit by President Clinton is a central plank in that strategy.

A senior aide now talks about completing "a virtuous circle" in Northern Ireland. He uses the analogy of Europe rebuilding with the aid of the US after the second World War.

First comes the settlement, then the political and economic input from the US government, then finally, in a land at peace and with a highly-educated workforce, comes the American corporate investment to create jobs and opportunity.

"We have the settlement and now we need to work on the rest of it," said the staffer. "We are convinced, even more so after Omagh, that the political framework now in place can absorb almost any body blow."

The White House has no illusion, however, about how difficult the task ahead still is. "It took 50 years to rebuild Europe," says the aide. "This will need to go on long beyond the Clinton presidency."

Mr Jim Lyons, President Clinton's economic adviser on Ireland - the job held by Senator George Mitchell before he left to chair the peace talks - agrees.

"Our greatest legacy on Ireland will be to institutionalise this issue with the American government, to ensure that every future administration will continue the policy this President has started. That is the long-term strategy," he says.

The US is prepared to be patient. They know the euphoria is long gone and that after a sullen marching season and the tragedy of Omagh, the President faces a completely different Ireland from the one he visited in November and December 1995. "The people of Ireland have changed adversity to opportunity," said a key staffer, "but we all know there is still a very long way to go."

They caution about expecting too much in the short term from a peace process that could need a generation to take firm root.

The US believes it has much to contribute. The White House points out that alone of the three leaders who began the process - Mr Albert Reynolds, Mr John Major and Mr Bill Clinton - the last is the only one left in place.

They also say that it was President Clinton who urged and encouraged both Mr Blair and Mr Ahern to give the issue their highest priority after they came to power and that, in the case of Mr Blair in particular, Mr Clinton's support and concern has weighed heavily.

As an example of his efforts they point out that on a recent Sunday night, less than 24 hours before his famous confession speech when he was huddled with his lawyers, Mr Clinton took time to call Mr Blair to discuss the aftermath of Omagh.

It is this continued commitment and a gritty realism about what is possible which dominate White House thinking on the eve of the second visit by the President to Ireland. As usual, the preparations are meticulous.

As he concludes his holiday in Martha's Vineyard this weekend, President Clinton will be poring over Irish books and briefings which staffers have prepared for him.

Among the books sent to him were John Ardagh's Ireland and the Irish, described by the publisher as "an account of how Ireland is changing today"; Tim Pat Coogan's The Troubles, one of the definitive works on events in Northern Ireland; Conor O'Clery's The Greening of the White House about the US role in the peace process, and a slim volume of poems by William Butler Yeats.

"He likes to soak in the atmosphere," said a senior staffer. "He absorbs information about Ireland; there's actually very little he doesn't know about the country." In recent times W.B. Yeats has become a favourite poet, the staffer says.

There are obvious wider ramifications of the visit. At a time when his presidency is in peril, Mr Clinton's Irish trip is shaping up as far more than just a victory lap for his role in the peace process, as some detractors allege.

Indeed, even those most cynical about this President in the American media concede that Ireland is a special case, and that his involvement in helping bring peace far exceeds any political considerations.

Mr Clinton, for instance, has visited only a handful of countries twice in his presidency, and Ireland now joins that exclusive club. The planning for it began almost immediately after his first trip.

His most wounding critic is probably Maureen Dowd, star columnist with The New York Times, who has turned her acerbic pen on him repeatedly in recent months.

But Ms Dowd, whose father was from Co Clare, gives Mr Clinton credit on Ireland, describing his last visit there as the highlight of his presidency.

Likewise with Jimmy Breslin, the legendary Newsday columnist who says he would have given up on Mr Clinton long ago were it not for his Irish politics.

As he needs all the help he can get to change the subject with the scandal-obsessed media, the Irish visit comes at an important time for the President.

He has prepared well for it. Mr Lyons says Mr Clinton's renowned political skills are never more in evidence than when he discusses Irish politics with him.

"He will go through each of the Northern Irish parties and describe acutely what each of them needs in order to move the process further. He has an extraordinary feel for the issue, and what motivates each of the players."

A senior White House staffer concurs, saying that during briefings from staff members on Ireland, Mr Clinton will often take over the session and hold a seminar on the topic.

"He intuitively knows how to work with people who have nothing in common. He knows politics is about win-win, not a zero-sum game. He understands what each side needs, and what each side faces," says the staffer.

On Tuesday of this week Ireland was again very much on the President's mind as his staff debated whether or not he should go to Omagh. The argument was that to go would be to confer retrospective legitimacy on an act of terrorism that shocked even the hardened hands in the White House.

"The leader of the free world does not visit terrorist bombing sites," said a staffer.

Mr Clinton himself, however, overruled such considerations and gave the green light to the visit. "He understood, instinctively, that the dynamic of the visit had changed overnight," said the staffer. "He knew that Omagh had to be a centerpiece, that he needed to catch the mood and to reach out to those who had suffered there."

It is this ability to catch and synthesise the political mood that has worked for Mr Clinton throughout his political career. Despite the Lewinsky affair he will arrive in Ireland with the highest approval ratings of any second-term President this century. But it is his legacy that has begun to preoccupy him now, and peace in Ireland is shaping up as a large part of that. Above all, he will be hoping his trip advances that cause.

Niall O'Dowd is the founding publisher of The Irish Voice in New York