Bertie Ahern dramatically announced his departure as Taoiseach today as pressure mounted over Mahon Tribunal revelations over his personal finances.
But Mr Ahern firmly denied his resignation had been sparked by the tribunal developments.
The Republic's second longest-serving Prime Minister revealed he will resign both as Taoiseach and leader of Fianna Fail on Tuesday, May 6.
The date will be shortly before Ian Paisley is likely to stand down, also as both First Minister and DUP leader, following the major international economic conference in Belfast from May 7-9.
It will mean that of the five leaders who squeezed together on Stormont sofas on devolution day last May 8 - Mr Ahern, Mr Paisley, Tony Blair, Secretary of State Peter Hain and Martin McGuinness - only the Deputy First Minister will remain in office.
And Mr McGuinness' party leader, Gerry Adams, will be the only main political party boss still in office just over ten years after the calendar date of the Good Friday Agreement - April 10, next Thursday.
Mr Ahern today insisted on one truth above all - that he has never put personal interests above the public goodwill.
He said he had never abused any public office and was confident that the Mahon Tribunal, where he was today facing a showdown over his personal finances, would conclude there had been nothing improper.
While conceding some people would view aspects of his personal finances as unusual, Mr Ahern stressed he has never been dishonest.
"While I will be the first to admit that I've made mistakes in my life and in my career, one mistake I've never made was to enrich myself by misusing the trust of the people," he told a Press conference, flanked by cabinet ministers from his party.
"I have never received a corrupt payment and I've never done anything to dishonour any office that I've ever held."
He said a simplistic analysis of today's announcement would suggest it had been brought forward by the Mahon Tribunal, however, after a period of reflection, he had wanted to "refocus the political dynamic in this country".
But Mr Ahern admitted tribunal-related matters had begun to dominate the political agenda at a very important point for the country in terms of the economy and the Lisbon treaty.
"I know in my heart of hearts I have done no wrong and wronged no-one," he said.
"My decision is motivated by what is best for the people. It is a personal decision.
"I will not allow issues related to my own person to dominate the people and the body politic."
Mr Ahern will resign after he makes an historic address to both houses of Congress in Washington - only the fourth statesman to be invited to do so, following Mr Blair - and a state visit from Japan.
The so-called 'Teflon Taoiseach' also pointed to the Good Friday Agreement as the major achievement of his time in office. He memorably returned to the negotiations at their most delicate stage immediately from his mother's funeral. The Agreement he said remained the political framework, with new prosperity both north and south, for the island of Ireland to reach its full political potential.
"The priority I put above all others was to work for peace on this island, and I have given all to that cause," Mr Ahern said.
He has been under increasing pressure to explain a series of issues surrounding his personal finances in the early 1990s.
Opposition party leaders were recently demanding clarification about conflicts of evidence at the long-running tribunal investigating payments to politicians and planning corruption.
While he has consistently denied any wrong-doing, pressure increased in the last week when two of the Taoiseach's ministers in the coalition cabinet - John Gormley, leader of the Green Party, and Progressive Democrat leader Mary Harney - both demanded further clarification.
Still only 56, Mr Ahern is the most successful politician in the Republic since Eamon de Valera.
He has been Irish premier since June 1997 and has been a member of the Irish Parliament for 31 years. He said he had been delighted to be elected 10 times, nine of them for Dublin central, and as Taoiseach three times.
'The best and most skilful of them all'
By Chris Thornton
It remains a defining moment in the drive for the Good Friday Agreement: a decade ago, Bertie Ahern stepped off a helicopter dressed in black and with a sombre face walked into Castle Buildings to resume negotiations for a settlement in Northern Ireland.
The Taoiseach had flown to Belfast directly after the funeral of his mother - an extraordinary commitment to the talks that showed two things: how important those talks were, and how devoted Bertie Ahern was to achieving a peace package.
In the speech announcing his resignation today, Mr Ahern mentioned Northern Ireland and the Agreement several times, listing the settlement as one of his major achievements in office.
Certainly he was an important part of the formula that brought it about, bringing an exceptional acute understanding of republicans (his parents had both been members of the old IRA) and an almost magic personal charm.
His 50th wedding anniversary gift to Ian and Eileen Paisley during the St Andrews negotiations - a walnut bowl carved from a tree that grew on the Boyne battlefield - was an example of how he could turn a simple gesture in a deft, telling political tool.
His predecessor as Taoiseach, Charles Haughey, famously described Ahern as " the best, the most skilful, the most devious, the most cunning of them all" .
It was an assessment that could have hindered Ahern considerably, but it probably added to his mystique. His career showed it was also almost certainly right.
Patrick Bartholomew Ahern is a consummate politician who managed the knack of not projecting himself like a politician.
He reportedly enjoys nothing more than canvassing his North Dublin constituency, a weekly routine he maintained throughout his decade as Taoiseach.
He tramped from house to house, pub to supermarket in an unfashionable coat that made him look more like the accountant that he initially trained to be than a national leader.
It helped maintain an extraordinary understanding of voters and maintain that image as an ordinary north Dublin bloke, mad about Man Utd and fond of a yarn.
Against expert opinion he called on all his skills to lead Fianna Fail to victory in last year's general election. It was a historic triumph: making him the first Taoiseach to win three successive terms, second only to Eamon De Valera in overall time in office.
In the end, the pressure of his opaque financial affairs appears to have been too much for the party he sustained. "One mistake I've never made is to enrich myself at the public purse," he said as he announced his resignation, his soft trademark grin still playing about his face.
Perhaps that smile wasn't difficult. Whatever the Republic's financial probes throw up for him now, it's probably a footnote to his achievements.
Bill Clinton, Tony Blair and now Bertie Ahern: the national leaders who delivered the Good Friday Agreement have consigned themselves to the history books.
Political friends and foes add to tributes
By Noel McAdam
Tributes to outgoing Toaiseach Bertie Ahern were today coming from across the political spectrum - and the border.
Former Prime Minister Tony Blair paid tribute to Mr Ahern for his role in the Northern Ireland peace process.
Mr Blair said: "Bertie Ahern was a great Taoiseach, a leader for whom I had the greatest respect, admiration and friendship.
"He will always be remembered for his crucial role in bringing about peace in Northern Ireland, for transforming relations between Britain and the Irish Republic and for presiding over a sustained period of economic and social advance in Ireland.
"He was also a key figure in Europe. He will have, deservedly, a central place in his nation's political history and much more widely. A remarkable man with a remarkable record of achievement."
Prime Minster Gordon Brown said Mr Ahern had been an "outstanding statesman".
He said: "I heard with great regret the news today of Bertie Ahern's decision to stand down next month as Taioseach.
"Bertie Ahern has been an outstanding statesman and has made an historic contribution in helping to bring peace to Northern Ireland, transforming Ireland's relationship with the UK and playing a key role in the development of a forward-looking and dynamic Europe.
"The UK could not have had a better partner. I wish him and his family well. We look forward to working with his successor towards continued peace and prosperity in both our countries."
Deputy First Minister Martin McGuinness said: "Few people have given as much of their time and energy to the peace process here as Bertie Ahern.
"He has been deeply involved for many years and the personal input that he made was reflected when he came straight from the graveside of his own mother to participate in a particularly delicate stage of the negotiations."
Secretary of State Shaun Woodward said one of the main architects of the peace process would be "hugely missed".
"His tireless dedication and commitment to transforming Northern Ireland will never be forgotten. We all owe him a huge debt," he said.
The first statement, however, came from Irish President Mary McAleese who said Mr Ahern's contributions to our thriving economy and to peace in Northern Ireland were hugely important. Bertie Ahern will be remembered as one of the outstanding politicians of his generation both nationally and internationally," she added
The first Northern Ireland response was from SDLP leader Mark Durkan who said while he had differed with Mr Ahern over the years he had never doubted his motivation or purpose
"Rather than speculation about issues around his resignation the SDLP want to reflect today on Bertie Ahern's positive record," the Foyle MP added.
"His commitment to the North has been shown in his constant involvement either in implementing the Agreement or in initiatives to secure its implementation. This good work involved not just high profile, high wire negotiations, but a lot of diligent private engagement with many interests."
The DUP's Nigel Dodds said: "Bertie Ahern was clearly held in high regard by the people of the Republic of Ireland, as evidenced by the fact that he was elected to the post of Prime Minister on three separate occasions and nobody can question that he was committed to establishing a strong working relationship between his own country and this part of the United Kingdom.
"The DUP has always sought to ensure that the relationship is one that is mutually beneficial."
Ulster Unionist leader Sir Reg Empey said: "By removing Articles Two and Three from the Republic of Ireland's Constitution he was able to improve the relationship between unionists and the Republic that had been bedevilled by this issue for so long."
Alliance leader David Ford said Mr Ahern had served with remarkable distinction and had been a very positive and constructive figure often during difficult stages in the peace process. "Unlike some others, he was prepared to extend the hand of friendship to Northern Ireland."
- 1951: Born in Dublin
- 1977: Elected to the Dáil
- 1991-1994: Minister for finance
- 1994: Fianna Fáil leader
- 1997: Taoiseach
- 2002: Re-elected
- 2007: Leads Fianna Fáil to third election victory, begins third term as Irish PM