Eamon Ryan is seen as the favourite to win the Green Party leadership contest.
Votes are being counted with a result expected on Thursday evening.
Votes will be counted through the day to see whether Eamon Ryan or Catherine Martin will lead the party through its time in government.
Mr Ryan is seen as a slight favourite to retain the leadership, but it is thought it will be close.
The result is expected around 7.00pm.
Aoife Moore is political correspondent with the Irish Examiner.
She told Breakfast Briefing: "Within the party itself, there's an acceptance from most people that Eamon has the lead on Catherine, especially with the success of the Programme for Government.
"I think it kind of came as no surprise to a lot of people that Eamon had been bolstered with the membership after the Programme for Government.
"Although Catherine's well-liked within the party, we can't see her overtaking him at this stage in the leadership contest."
"They start counting this morning, they're expecting about 2,000 postal votes to come in today.
"Although there was about 3,000 people eligible, only 2,000 voted".
"They're going to make an announcement and it'll be then live video stream with Catherine and Eamon both there".