Ireland's Green Party withdrew Sunday from the Irish government, raising pressure for Prime Minister Brian Cowen to resign from office and for Ireland to hold a national election sooner than March 11 as planned.

Green leader John Gormley said his small party _ critical for the survival of Cowen's coalition government _ would immediately join the opposition side of the parliament.

Gormley stressed that his lawmakers would support the last essential deficit-fighting measure facing a parliamentary vote, the 2011 Finance Bill _ then join other opposition forces in requiring a February election.

"The Irish people want to see political certainty, economic certainty, and they do want an election," said Gormley, whose environmentalist party joined the Irish government in 2007.

Cowen said the Greens' withdrawal made it essential for all parties to reach an agreement within the next few days on speedy passage of the Finance Bill, which will broadly raise income taxes as part of Ireland's international bailout.

He ruled out resigning as prime minister before that legislation becomes law.

"It's important that we get the Finance Bill through, and we need a government to do that," said Cowen, who did resign Saturday as leader of Ireland's political heavyweight, the Fianna Fail party. It is expected to suffer heavy losses in the election.

Sunday's Green withdrawal means Cowen has already lost two more Cabinet ministers: Environment Minister Gormley and Communications Minister Eamon Ryan. Cowen has only seven of 15 Cabinet ministers remaining _ the bare minimum permitted by Ireland's constitution _ following his disastrous management of an attempted Cabinet reshuffle last week.

The two major opposition parties, Fine Gael and Labour, are threatening to force a no-confidence vote in parliament this week against Cowen unless he promises to get the Finance Bill passed by Friday.

Cowen and Gormley both agreed Sunday, however, that the bill was so complex and wide-ranging that it must receive more time for debate and amendment.

"It's not possible to deal with it in a week," Cowen said.

Gormley appealed to Fine Gael and Labour to hold fire until the Finance Bill is passed by the fastest responsible means possible.

"We do need some certainty around the Finance Bill. It does need to pass. It's genuinely in the national interest that that happens," Gormley said.

The loss of support from six Green lawmakers means Cowen can no longer muster a parliamentary majority. If he lost a confidence vote he would be obliged to resign immediately and call an election within four weeks.

All sides agreed that the Green decision means the March 11 election date announced last week by Cowen is null and void. Analysts said a new election date, most likely in the second half of February, would be pinpointed this week.