The Green Party leadership faces its strongest challenge since entering government when party members debate motions for and against the Lisbon Treaty at a special convention to be held in Dublin today.
There was a consensus last night that a majority at the convention would vote in favour of the treaty, but there was considerable doubt about the prospect of achieving the two-thirds support required to adopt an official party policy on the issue.
Supporters of a Yes vote were described as "far from confident" about their prospects of securing the necessary two-thirds majority. Senior party sources stressed the need for a strong performance by the party leadership in order to sway the doubters and the undecided, in what is likely to be an impassioned debate.
Meanwhile, former Dublin MEP Patricia McKenna, who is leading the No side, was equally unsure about securing sufficient support to block a two-thirds majority in favour of the treaty.
"I'm concerned that they might get a two-thirds Yes vote in view of the strong support from the parliamentary party," she said. Earlier this week, the party's six TDs and two Senators unanimously urged support for the treaty.
There was considerable interest in whether Minister of State for Food and Horticulture and former party leader Trevor Sargent, still a highly-influential figure in the party, would participate in the treaty debate. He is not a listed speaker but may get an opportunity to take part in the general discussion, where speakers will be chosen by lot.
The day looks likely to begin with a procedural wrangle and leading speakers against the treaty have already called for the treaty issue to be decided by secret ballot rather than a show of hands, as at present.
In a joint statement, Ms McKenna and party activists Martin Hogan and Martin O'Keeffe said there was "considerable unease among members, on both sides of the debate, that the party leadership, who have very publicly backed the Yes side, are insisting on an open vote tomorrow".
The statement continues: "We believe that the non-secret manner of a simple show of hands undermines the principles of balance and democracy . . . "
They also object to the debate being chaired by Senator Dan Boyle, who has already declared his support for the treaty. "We also believe that in the interests of balance, democracy and openness, overall speaking time must be allocated on a strict 50/50 basis between the Yes and No sides of the debate. This is not the case," the statement adds.
Rejecting these arguments, a spokesman for Minister for the Environment and party leader John Gormley said: "These arrangements have been known for the past month and it is not reasonable to raise objections on the eve of the convention. A secret ballot on the three motions involved would be impracticable and unprecedented."
Meanwhile, Green Party founder Christopher Fettes has publicly backed a Yes vote on the treaty. It was a letter to The Irish Times in late 1981 from Mr Fettes which led to the inaugural meeting of the Ecology Party, later renamed as the Green Alliance and subsequently the Green Party.
In an open letter to today's convention, Mr Fettes concedes he still has doubts about whether Ireland did the right thing by endorsing projects such as the single currency, but concludes that these decisions have now been taken and it is time to move on politically.
The letter was sent to party chairman Senator Dan Boyle with a suggestion that it be read out during the debate. Despite his reservations Mr Fettes argues that "Ireland has benefited so extensively from EU supports since we joined that it ill becomes us to take too selfish a line today".
Green Party councillor for Clontarf, Bronwen Maher, has called on members to oppose the treaty. In a statement, she claimed the treaty obliged Ireland to build up its military capacities while consolidating the European Defence Agency.