A Green Party councillor says she believes Sinn Féin will secure an "absolutely massive majority" in the next Dáil if Fianna Fáil insists on putting them into opposition for now.
Lorna Bogue - Councillor for Cork City South East - says Mary Lou McDonald's party has been 'excluded' from government formation talks with Fianna Fáil and Fine Gael.
It comes as the Green Party parliamentary has agreed to enter negotiations with FF/FG about a potential programme for government - although any agreement would need the support of two-thirds of the party's members.
Eamon Ryan is due to meet with Micheál Martin and Leo Varadkar today to discuss the next steps in the process.
Niall Collins, Fianna Fáil TD for Limerick, and Lorna Bogue spoke to The Pat Kenny Show this morning about the latest developments.
Deputy Collins suggested: “We as a Fianna Fáil parliamentary party took a decision to pursue a course of action.
“When we hear the narrative of Sinn Féin, dismissing Fianna Fáil and the other parties, they’re basically dismissing our mandate."
However, that suggestion was sharply criticised by Cllr Bogue.
She said: “There was a document that was sent out to every party except Sinn Fein by Fianna Fáil and Fine Gael.
"Sinn Féin has been excluded from this process.
“If Sinn Féin didn’t receive a correspondence from Fianna Fáil and Fine Gael… how are they dismissing it?"
She claimed she believes the process to date "has been about making Micheál Martin Taoiseach".
Cllr Bogue added: “I’m just still flabbergasted at this idea that Sinn Féin has not been involved in the negotiations through their own problem - they were not approached by Fianna Fáil and Fine Gael.
“At no point were Sinn Féin involved in any of this. If Fianna Fáil wants to put them into opposition, I tell you now they will come back with an absolutely massive majority next time."
Deputy Collins insisted he had "no issue with Sinn Féin’s mandate" and respects it - but suggested Mary Lou McDonald's party "should recognise and respect" the mandate of other parties.
Elsewhere, Deputy Collins said there'd been a small amount of 'pushback' within the party about the prospect of a coalition with the Greens, although said there has been more opposition to the idea of an arrangement with Fine Gael.
However, he said he believes there's a "silent majority" of party members who recognise the need to form a government as soon as possible.
The Limerick TD also said some of the environmental red lines being put forward by the Greens are 'unsettling' to some Fianna Fáil members.
However, Cllr Bogue said it shouldn't be a surprise that the Greens are pushing for such measures.
She said: “The idea that the Green Party would have the temerity to have red lines going into negotiations is quite amusing to me.
"We as a party have been campaigning on environmental issues for 40 years, so it shouldn’t be surprising that we would enter into a negotiation saying we have red lines."