Fine Gael leader, Mr John Bruton, has called the challenge to his leadership by party front benchers Mr Michael Noonan and Mr Jim Mitchell a "serious misjudgment".
Mr Bruton pledged to defeat the motion of no confidence in his leadership which will be tabled by the two senior Fine Gael TDs this week.
Mr Noonan told ireland.comthe decision to table the motion came after widespread consultation with the parliamentary party. He said he believed "there is a clear majority in favour of the motion."
Mr Bruton's position came into question after an Irish Times/MRBIopinion poll on Friday showing plummeting ratings for both the party leader and the party itself.
But Mr Bruton described today's challenge as a serious misjudgment and a major opportunity to the party's opponents. Speaking on RTE News he said: "I believe it is very important not only that I fight this but that I win."
Saying one opinion poll does not justify reopening decisions about the leadership of a party which had been reached by democratic vote a few weeks ago. He added: "It is vital for Fine Gael that this particular challenge be defeated."
Mr Noonan said if the motion was successful, both he and Mr Mitchell would put their names forward as candidates for the new leader on the agreement that if either is successful, the position of deputy leadership would be offered to the other. He added there may also be other candidates for the position.
The motion is expected to be put to a meeting of the 73-strong Fine Gael parliamentary party next Wednesday.
In a joint statement, Mr Noonan and Mr Mitchell said Fine Gael needed a new beginning.
They blamed Mr Bruton's style of leadership for their party's failure to capitalise on the "successive scandals" associated with Fianna Fail and Fine Gael's failure to connect with the electorate. They said the leadership lacked "genuine consultation with the front bench and the parliamentary party.
- Mr Bruton (53) has been leader of Fine Gael since 1990, taking over from Mr Alan Dukes, now a member of his shadow cabinet. He became Taoiseach in 1994, without having to win an election, when the Fianna Fail party's Mr Albert Reynolds stepped down, and led a three-party coalition until being defeated in an election (1997).
- Mr Noonan (57) has been an outspoken figure in Fine Gael for almost 20 years and questioned Mr Bruton's leadership on a previous occasion.
- Mr Mitchell (54) is one of the most experienced members of the current Fine Gael team. He won plaudits last year for the report of a joint parliamentary committee he headed which directed strong criticism at banks and other financial institutions for the non-payment of a controversial tax on customers' accounts.
Additional reporting PA