A Green Party senator texted colleagues after the leadership election, saying: "fuck her" about deputy leader Catherine Martin and accused the returning officer of being a "Sinn Féin front".
Róisín Garvey, a senator from Clare, was supportive of Eamon Ryan's leadership campaign and was included in a Whatsapp messaging group with those who had backed Mr Ryan's re-election.
After Mr Ryan's win, in which he pipped Ms Martin to the post by 48 votes, Ms Garvey wrote to the group: "She tried to bring him down and failed. Fuck her a win is a win. Well done everyone," in a message seen by the Irish Examiner.
Later that night, Ms Garvey confronted the election's returning officer Harry McEvansoneya, who is also the secretary of the party's policy council, on Dublin's South William Street after they had left the hotel where the results had been announced.
A number of sources have confirmed Ms Garvey accused Mr McEvansoneya of being a "Sinn Féin front" and accused him of bias against Mr Ryan.
A source with knowledge of the incident said Ms Garvey was "belligerent", and left after she was asked if she "believed" in the party.
It's understood no official complaint to the party has been made about the incident.
Ms Garvey has received a number of complaints about her behaviour previously.
After party leader Eamon Ryan used a racial slur in the Dáil last month, Ms Garvey defended the party leader, later going on to use the word 'bigger' in another WhatsApp group in reference to Mr Ryan's slur, which led to two complaints against her, which has been confirmed by a party spokesperson.
One of the complainants, Niamh O'Reilly, said she withdrew her complaint as she was afraid she might be suspended from the party.
She has since left the Greens, saying: "We couldn’t or wouldn’t even hold a senior member accountable for saying a slur, no one was ever held accountable for anything really when legitimate complaints were sent."
Ms Garvey has been approached by the Irish Examiner a number of times for comment
After being approached by the Irish Examiner, a Green Party spokesperson said: “After being contacted in relation to the remarks, Senator Garvey brought the incident to the attention of the party.
She also contacted Minister Martin and apologised.
“Senator Garvey said that the comment was made during a heated moment and does not reflect how she feels and added that she has the utmost respect for the deputy leader.
“Minister Martin has accepted the apology and they look forward to continuing to work well together.
“The incident has been reported and a disciplinary process has been initiated.
“The Green Party does not tolerate abusive behaviour and every incident that is reported to the party is followed up on.”