Messages of congratulations have been sent to John Gormley following his election as leader of the Green Party.
Mr Gormley, who is the Minister for the Environment, won two-thirds of the votes in the contest.
Labour Party leader Pat Rabbitte was among the first to send congratulations.
Mr Rabbitte said Mr Gormley's success in becoming leader was no surprise to anyone who had observed his journey in politics and he wished him well in the job.
775 members of the party, roughly 60% of all of those eligible to vote, participated in the postal ballot, which closed at midday.
Minister Gormley, the Green TD for Dublin South East for the last ten years, was elected leader with 478 votes.
Former MEP and general election candidate in Dublin Central Patricia McKenna received 263 votes.