Taoiseach Bertie Ahern has announced that he will tender his resignation to President Mary McAleese on 6 May.
In an emotional speech surrounded by his Government colleagues, Mr Ahern expressed thanks to his supporters over more than three decades in the corridors of power.
He said his announcement was solely motivated by what is in the best interests of the people and said recent developments had not motivated his decision.
However Mr Ahern said he had no doubt that a simplistic analysis will suggest that his decision was influenced by more recent events at the Tribunal.
Mr Ahern insisted he had never put personal interest above the public good.
'I have never done anything to corrupt my office' he said. 'I know in my heart of hearts that I have done no wrong and wronged no one.'
During the statement at Government Buildings, the Taoiseach stressed that he had never received a corrupt payment.
He said he feared 'the constant barrage' of commentary on tribunal-related matters would continue to dominate the political agenda at what he described as 'an important point for our country.'
Surrounded by his ministers, he said he had been humbled with 'the great responsibility' of leading the nation and expressed his belief that all levels of Irish society had seen their well being improved while he served as Taoiseach.
Mr Ahern said it was an extraordinary honour to be elected as Taoiseach and gave his thanks to his Fianna Fáil colleagues.
He also acknowledged the steadfast support from the coalition parties and Independents who supported his Government.
'Just as stability is important in a coalition Government, it is even more vital in a political organisation.'
Mr Ahern said he had first sought election to the office of Taoiseach on the pledge that he would put people before politics. He had kept that promise.
He said he had always placed the interests of the Irish people above his own. Therefore, he would not allow issues relating to his own person to dominate the body politic as this would be contrary to the long-term interests of the Irish people.
The Taoiseach stressed he wanted everyone to understand one truth above all else: never in all the time that he had served in public life had he ever put his own personal interests ahead of the public good.
Mr Ahern said he had provided more details about his own personal finances than any person in public life who had held office.
And while he was the first to admit that he had made mistakes in his life and in his career, one mistake he never made was to enrich himself by misusing the trust of the people.
Mr Ahern said he had never done anything to dishonour any office that he had ever held.
11 years as Taoiseach
Bertie Ahern has been Taoiseach for almost 11 years.
Prior to attaining the highest office of Government, he held most of the important cabinet portfolios including Finance, Labour and Industry and Commerce.
He gained worldwide attention for his role in striking the Good Friday Agreement for which all sides on the political divide recognised his important vital contribution.
His career in politics began at 17 years of age when he joined Fianna Fáil.
He became a TD in 1977 and began to progress up the party hierachy.
In 1987 he was made Minister for Labour. He later spent periods as Minister for Industry and Commerce and Minister for Finance.
Following the collapse of the Fianna Fáil / Labour Government in 1994, Mr Ahern was elected leader of his party and three years later, he led Fianna Fáil into coalition with the Progressive Democrats.
During his time as Taoiseach he has won acclaim for the role he played in the peace process - helping to negotiate the Good Friday Agreement in 1998.
His spell in office has also seen a period of record economic growth and prosperity, but has been plagued by questions about his financial affairs in the 1990s.
Bertie Ahern is the first Fianna Fáil leader since Eamon De Valera to have won three terms in office for his party.