The role President Clinton played in the peace talks is regarded as vital. Yet it is one that the US Administration felt obliged to play down in case it could be seen as undue outside interference and arouse unionists' suspicions of American intentions.
Earlier this week, soon after his return from Africa, President Clinton spoke to Tony Blair and offered to help in any way with the talks. It is not known if the British Prime Minister took him up. On Tuesday President Clinton called Bertie Ahern to sympathise with the death of his mother and to discuss the situation reached in the peace talks.
The US was not exactly on the sidelines during the drawn-out negotiations which began almost a year ago, but neither was it on the field as an active participant alongside the two governments and the political parties. "Facilitator" was a word often used to describe the role as distinct from "mediator" which the US insisted it was not.
What was never in doubt was President Clinton's own personal commitment to the search for a lasting peace. In recent years he rarely made a speech about foreign affairs in which he did not refer to Northern Ireland as one of the areas of the world where the US was pressing for a peaceful solution as in the Middle East, Bosnia and other trouble-spots.
Time and again the President assured those who would "take risks for peace" in Northern Ireland of the full backing of the US. The other side of the coin was that those who would resort to violence would always be condemned.
He was a risk-taker himself when he was persuaded - against the advice of the State Department, the Department of Justice and British diplomats - to allow Gerry Adams to visit the US while the IRA was still bombing British cities and killing people in Northern Ireland.
When the first IRA ceasefire was declared in August 1994, that risk was seen to have paid off. When the ceasefire was broken in February 1996, US outrage was manifest and the doors of the White House closed to Sinn Fein, while remaining open to loyalists with links to paramilitary organisations which were respecting the ceasefire.
When negotiations moved into an active phase last September, the US publicly acted as cheerleader, but behind the scenes there were constant exchanges between the President's national security staff and the political parties as well as the two governments. The White House officials never lifted the cloak of confidentiality from these exchanges, but they were said to be exhortatory rather than banging the tables.
One of the most important elements of US help to the peace process was the assigning of George Mitchell and a small staff, first as economic representative, then to chair the decommissioning commission and finally to take over the chair of the peace talks themselves.
At an earlier stage a small group of dedicated Irish-Americans had helped to bring about the IRA ceasefire by establishing confidential channels between Sinn Fein/IRA and the White House and so helping push the republican movement towards the negotiating table.
The group which visited Belfast and was instrumental in bringing Gerry Adams to New York for a well publicised visit included influential business leaders Bill Flynn and Charles "Chuck" Feeney, journalist Niall O'Dowd and former congressman Bruce Morrison.
On Capitol Hill, influential voices that the President heeded on Irish affairs were those of Senators Ted Kennedy and Chris Dodd who had their own lines into the peace process. Senator Kennedy's sister, Jean Kennedy Smith, had, of course, been appointed to Dublin as ambassador at a critical time.
In the House of Representatives, the Ad Hoc Committee on Irish Affairs, with about 100 members, kept a watchful eye on the twists and turns in the peace process and made little secret of its support for nationalist claims and especially in the areas of human rights and equality. The four co-chairmen, Ben Gilman, Tom Manton, Peter King and Richard Neal, wrote numerous statements, calling for fair treatment for nationalists and criticising what they saw as unionist intransigence.
This committee will closely watch Sinn Fein's attitude towards any agreement.
The St Patrick's Day reception at the White House this year gave President Clinton an unprecedented opportunity to meet all the political leaders in the peace process as the negotiations reached the crucial phase. He made good use of it to impress on the politicians that this was "the chance of a lifetime for peace in Ireland" and that "no one will be the loser if agreement is reached".
He promised them the party to end all parties next year if they pulled it off.