Former Green Party TD John Gormley is to step down as party leader.
In an email to party members, Mr Gormley said that following on from the General Election result the party had to reinvent itself, and said he would not be seeking re-election as party leader.
The Greens went into the last election with six TDs and came out with none.
Under internal rules, a leadership contest must be within six months of a General Election.
It is likely that Mr Gormley, who became leader in 2007, will stay in the post until May when a new leader is chosen.
Around 1,000 members will be entitled to vote in the postal ballot to according to one party source.
In his email, Mr Gormley said the Greens 'temporary demise' has been interpreted by others as a rejection of the green agenda and said this is reflected in the retrograde steps announced in the new programme for Government.
He said this shows that the party is needed now more than ever.
Party members will gather next weekend for the first time since the Election to discuss its future.