There has been mixed reaction to Bertie Ahern's announcement that he will resign as Taoiseach in five weeks' time.
The Opposition has described the decision as inevitable, while politicians in Northern Ireland and abroad have praised Bertie Ahern's role in the peace process.
After 11 years as Taoiseach, the announcement came on the steps of Government Buildings, in a 12-minute statement with Cabinet colleagues beside him.
Bertie Ahern said the anniversary of the Good Friday Agreement had prompted him to take stock of his own position.
Mr Ahern had intended to review his position after next year's local elections, but in the light of the distractions caused by the Mahon Tribunal he decided to bring forward his decision.
People all around Ireland have been reacting to the Taoiseach's resignation announcement with mixed emotions.
Some have been describing it as a 'sad day which has seen a decent man hounded from office'. Others say it 'may usher in a new era of transparency and accountability in Irish political life'.
President Mary McAleese complimented the Taoiseach on his achievements.
She said Mr Ahern's contributions to Ireland's thriving economy and to peace in Northern Ireland were hugely important. She said he deserves every credit for the work he has done.
President McAleese said Bertie Ahern would be remembered as one of the outstanding politicians of his generation, both nationally and internationally.
Fine Gael leader Enda Kenny has said that much of Bertie Ahern's good work will be overshadowed by recent events linked to the Mahon Tribunal.
He said whoever the new leader of Fianna Fáil is, he or she should seek a mandate from the people and let them decide what kind of government they want to lead them.
Mr Kenny said that the Taoiseach has bowed to the inevitable and claimed this day would have come earlier had Mr Ahern applied the standards he expected of others to himself.
Labour Party leader Eamon Gilmore also welcomed the announcement.
He said that he came to the conclusion many months ago that Mr Ahern would find it impossible to continue in office because of the mounting conflicts and contradictions between the statements he originally made about his financial affairs and the evidence uncovered by the Mahon Tribunal.
Mr Gilmore said that nobody would dispute the huge personal and political effort Mr Ahern put into securing a political settlement in Northern Ireland.
The acting leader of the Progressive Democrats, Mary Harney, said today's announcement was a great act of political dignity' and said it was the end of an era.
She said Mr Ahern had displayed great skills in keeping coalition governments together.
Green Party leader John Gormley praised the Taoiseach's recognition of the critical importance of issues like climate change and energy security.
He said that on that basis, he had opened the negotiations which ultimately put the Green agenda at the heart of Government.
British Prime Minster Gordon Brown said Mr Ahern had been an outstanding statesman. He said the UK could not have had a better partner.
Mr Brown said he had 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.
Former British Prime Minister Tony Blair also highlighted Mr Ahern's role in the peace process.
He said Mr Ahern was a great Taoiseach, a leader for whom he had the greatest respect, admiration and friendship.
Mr Blair said that he will always be remembered for his crucial role in bringing about peace in Northern Ireland, for transforming relations between Britain and the Republic and for presiding over a sustained period of economic and social advance in Ireland.
He said Mr Ahern will have, deservedly, a central place in the Irish nation's political history and much more widely.
Former Ulster Unionist leader David Trimble said he regretted Mr Ahern's departure as Taoiseach and said the Good Friday Agreement could not have been achieved without him.
Cardinal Seán Brady added his voice to the tributes, saying Mr Ahern's political career has been characterised by his hard-working style and his generous helping of those in need in his constituency of Dublin Central and beyond.
He also said it was due to Mr Ahern's initiative that the very significant process of Church-State dialogue had got under way and continues and this was another important element of his legacy.
SIPTU General President Jack O'Connor said Mr Ahern's time in office had seen 'the most dramatic enhancement of economic prosperity in our entire history'.
He praised the social partnership process, which he said served as a critical catalyst.
ICTU General Secretary David Begg also paid tribute to the work of the Taoiseach.
He said Mr Ahern had always treated unions with great courtesy and fairness.
US Senator Ted Kennedy issued a statement through his office, praising Mr Ahern as a 'steady and effective leader of the Irish people.'
Senator Kennedy said Bertie Ahern had been a good friend of America and a good friend personally.
He expressed his hope that the Taoiseach's unique talents would be of service in resolving conflicts elsewhere in the years ahead.
US Congressman Richard Neal, chairman of the Congressional Friends of Ireland, said he had been speaking to the Taoiseach this evening and was surprised at the announcement.
Praising Mr Ahern's role in the peace process, he said he applauds Mr Ahern's 'steadfastness in seeing it through.'
He said Mr Ahern had built many great relationships in the US and that plans were still on schedule to welcome the Taoiseach to Capitol Hill on 30 April to deliver his Joint Address to Congress.