Green Party deputy leader Catherine Martin voted against entering into official government formation talks with Fianna Fail and Fine Gael.
The Greens yesterday made the historic decision to begin formal negotiations with the two parties on how to form the next government.
Green Party leader Eamon Ryan will meet Fianna Fail leader Micheal Martin and Taoiseach Leo Varadkar tomorrow morning to begin negotiations.
However, it has emerged Mr Ryan's deputy leader was among a group of Green TDs who voiced objections to the move and voted against the proposal during a teleconference call yesterday.
Last week, Ms Martin was highly critical of comments by Tanaiste Simon Coveney, who said he will not agree to a 7pc a year cut in carbon emissions if it impacts negatively on rural Ireland.
Ms Martin described the Tanaiste's comments as "quite disturbing" and said she shared the views of those in her party who were concerned about going into government with Fine Gael.
A Green Party spokesperson said: "Catherine was against going into talks now because she felt greater clarity was needed on the issues raised with the two parties previously, as she expressed on the Sean O'Rourke show on Friday, but she respects the democratic votes of the party and is happy to participate in talks in good faith."
The party's 12 TDs held a vote on starting government negotiations with Fianna Fail and Fine Gael as they could not reach a consensus.
Those in favour of talks reached the two-thirds majority needed for the vote to be passed.
If the Greens' parliamentary party members agree a programme for government, it will also have to be passed by two-thirds of the membership before they can enter into a coalition.
The party has been racked with internal turmoil over the decision to enter into talks and has been meeting every day via video link to debate Fianna Fail and Fine Gael's policy framework document.
They sent the two parties a list of 17 questions relating to climate change and other key Green issues, such as ending direct provision.
Fianna Fail and Fine Gael agreed with the majority of their demands but were reluctant to sign up to a 7pc a year reduction in carbon emissions.
Over the weekend, the Greens sought more information from Fianna Fail and Fine Gael before agreeing to talks.
In a statement published after its vote, the Green Party said it was "conscious of the huge challenges" facing the next Government in the wake of Covid-19 crisis.
"The party will now work with Fianna Fail and Fine Gael to develop a deal that respects our mandate with a view to presenting that agreement to Green Party members for approval," it said.
"Any proposal must be transformative on climate action and commit to strong progress towards a more sustainable and fairer society.
"If this is not the case, Green Party representatives will withdraw from negotiations and pursue their mandate in opposition and work to hold the government to account."
Mr Martin and Mr Varadkar welcomed the decision by the Green Party to enter into formal talks.