Prime Minister Brian Cowen announced Saturday that he has resigned as leader of Ireland's dominant Fianna Fail party but intends to keep leading the government through the March 11 election.

Irish Prime Minister Brian Cowen, seen here as he pauses during a media briefing last November, announced his resignation as Fianna Fail party leader on Saturday. (Associated Press)

Cowen's surprise move capped a week of political crises that brought his coalition government to the brink of collapse.

Never before in Irish history has a politician sought to remain prime minister without being leader of the main government party.

Cowen pledged that the short-term split in power would not "in any way affect our ability to do our business."

Opposition leaders announced they would seek to oust Cowen as prime minister in a non-confidence vote next week in parliament.

Enda Kenny, leader of the main opposition Fine Gael party, said Cowen's "attempt to remain as head of government despite losing the confidence of his own party is another sad example of Fianna Fail putting their own survival ahead of the country's survival."

Kenny said the prime minister must resign from cabinet immediately and permit a national election sooner than March 11.

"If he refuses to do so, Fine Gael will move a motion of no confidence in Brian Cowen as Taoiseach [prime minister] in the Dail [parliament] on Tuesday," Kenny said.

Cowen said he was confident of winning that vote despite his narrow and fluctuating parliamentary majority.

Greens object to cabinet restructuring

Since Thursday, Fianna Fail legislators had been demanding Cowen's resignation as party chief after he bungled an attempted pre-election cabinet shuffle. He accepted five rapid-fire cabinet resignations in a calculated move to promote fresh faces into cabinet and boost their pre-election profiles.

But, inexplicably, Cowen failed to secure support beforehand from the other party in his coalition government, the Greens, who were caught off guard by the mass resignations and vetoed his plan as a cynical stunt.

The Green Party instead humiliated Cowen, forcing him to announce a March 11 date for an election that the embattled premier has sought to delay since November.

Cowen insisted Saturday he had taken his decision to resign as party leader only that morning over breakfast with his family, and had not discussed the move with other cabinet ministers.

"I'm concerned that renewed internal criticism of Fianna Fail is deflecting attention from this important debate," he said of the March election, which Fianna Fail is universally forecast to lose.

Cowen, who last week had rejected the notion that he could quit as Fianna Fail chief while remaining prime minister, conceded that his move was unprecedented since Ireland gained independence from Britain in 1922.

"This isn't the ideal situation, but we will manage the situation," he said.

PM wants to focus on deficit-fighting legislation

Cowen said by stepping down as Fianna Fail leader, he could focus purely on the immediate task of passing two pieces of deficit-fighting legislation linked to Ireland's November negotiation of an emergency €67.5 billion ($91.3 billion Cdn) credit line from the European Union and International Monetary Fund.

He said Fianna Fail would elect a new leader within days who would "prepare and move forward the organization for the [election] campaign itself."

Fianna Fail, which means "soldiers of destiny" in Gaelic, has won the most seats in parliament in every national election since 1932. It has formed governments following the past six elections dating back to 1987.

But all opinion polls over the past year suggest that Fianna Fail faces a historic thrashing by voters this time. The party stands at a record-low 14 per cent support in the most recent survey, in fourth place behind three opposition parties.

Cowen declined to speculate on who was most likely to succeed him. On Tuesday, he defeated a leadership challenge from Cork legislator Micheal Martin, who immediately resigned as foreign minister.

Analysts consider Martin and Finance Minister Brian Lenihan the two strongest candidates to win the imminent Fianna Fail leadership contest. A vote among Fianna Fail's 71 legislators could come as soon as Tuesday.

Other potential leadership candidates include cabinet ministers Mary Hanafin and Eamon O Cuiv, who is the grandson of Fianna Fail founder Eamon de Valera.