Taoiseach Brian Cowen has announced he will not contest the general election.
Mr Cowen (51) tonight said he had come to the decision following talks with his family and Fianna Fáil leader Micheal Martin.
Mr Cowen said it was time to give the new party leader and frontbench team he appointed earlier today "a break".
He stressed that Mr Martin had not asked him to stand down."Everyone in the Fianna Fáil party wanted to see me stand again," he told Midlands Radio 103.
Mr Cowen said he would remain strongly supportive of Mr Martin and the party. He believed the party's new leader could lead Fianna Fáil through a very good election campaign.
"Of course it's with a heavy heart you make a decision such as this," Mr Cowen added.
"It's a momentous decision for me, but also I think it's the right decision because the party now is in the process of rebuilding and rejuvenating and renewing, and a generational shift should take place of which I'm a part, certainly in terms of the tenure I've had as a prominent member of the organisation throughout the country for many years."
Mr Cowen said playing a role in the Northern Ireland peace process was his proudest moment in politics.
He said the Fianna Fáil organisation in the Laois-Offaly area had wanted him to contest the election, which is expected to take place on February 25th. He would not be drawn on speculation that his brother, Cllr Barry Cowen, would contest the election in his place.
A Fianna Fáil meeting took place in the Tullamore Court Hotel at 6pm this evening to make arrangements for a selection convention scheduled to take place in the constituency tomorrow night.
Mr Martin said he wanted to extend his best wishes to the Taoiseach.
"Brian Cowen has been a friend of mine for many years and I will always admire his sincere commitment and the sizeable contribution he has made to Irish public life," he said.
"He has given a high example in public service and he is a politician who has been motivated by the common good."
Mr Cowen was first elected in 1984 in byelection caused by death of his father, Bernard “Ber”’ Cowen.
He went to serve as minister for labour 1992-1993; minister for transport, energy and communications 1993-1994; minister for health and children 1997-2000; minister for foreign affairs 2000-2004; minister for finance 2004-2008 (tánaiste 2007-2008). He was elected Taoiseach in May 2008.
Mr Cowen will dissolve the Dáil tomorrow afternoon and the election date will then be set. The Dail will reconvene at 2.30pm with a statement from Mr Cowen which is expected to be followed by remarks from the leaders of Fine Gael, Labour, Sinn Féin and the Greens.
The Taoiseach will then attend Áras an Uachtaráin in the Phoenix Park to ask President Mary McAleese to formally dissolve parliament.
Minister for Social Protection Eamon Ó Cuív said it was with great regret he learned of Mr Cowen's decision.
"He is an intelligent and resourceful person with an underlying strength and determination to get the job done in the face of great challenges and against great odds," he said.
"As Taoiseach at a time of dramatic change in Ireland's economic circumstances he always put the country first. At Cabinet he had the capacity to work across a number of issues and could think originally and argue compellingly."
He said Mr Cowen had a "formidable intellect and the ability to forge partnerships".
"It was an honour for me to serve in his Government," he added.
