Tánaiste and Minister for Foreign Affairs Simon Coveney has said nothing can be ruled out, including another election, if the programme for government is not passed this week.
However, he countered this by saying he is a positive person and he believes the deal can be approved.
Speaking on RTÉ's Morning Ireland, Mr Coveney said this is a difficult week for Fine Gael, Fianna Fáil and the Greens because there is division in all three parties in how they view the programme for government.
He said the country desperately needs a government that has a majority and the authority to make decisions and he believes the coalition can be strong and radical.
Mr Coveney said in many ways Fianna Fáil and Fine Gael have been defined by how they have competed against each other at election time.
This, he said, is a new form of government. Politics has changed and the party must define itself by what it wants for the future, he said.
He warned there will be political uncertainty if this deal is not agreed.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
Tánaiste Simon Coveney has said nothing can be ruled out, including another election, if the programme for government is not passed this week pic.twitter.com/M8IDr5VDrL— RTÉ News (@rtenews) June 22, 2020
When asked about opposition to the deal voiced by Green Party TD Neasa Hourigan, Mr Coveney said that she was part of the negotiating team that signed off on the deal.
She did not get everything she wanted, he said, adding that "nor did I".
Mr Coveney said that the target of reducing carbon emissions is one of the most ambitious of any country in the world.
He said he believed it was unlikely that the target of reducing 7% emissions per annum will be reached every year, but the overall target could be reached by 2025.
Tánaiste Simon Coveney says the programme for government between Fine Gael, Fianna Fáil and the Green Party is a series of compromises, where no party got everything it wanted pic.twitter.com/TlJtdUOLIu— RTÉ News (@rtenews) June 22, 2020
It comes as a Green Party TD said it is "a close call" as to whether his party will support the programme for government, but he hopes there will be enough support to get it over the line.
Also speaking on Morning Ireland, Waterford TD Marc Ó Cathasaigh said the programme is a radical and transformative one.
He said there is a lot of change in the document and he is very proud of what the Green Party has managed to produce.
Mr Ó Cathasaigh said there is no way of reducing carbon emissions, year-on-year, to reach a 50% reduction in carbon emissions by 2030 without a root-and-branch re-jig of society and how we do things.
There are quick wins in terms of cycling, walking and travelling, he said, while other things, such as retro-fitting, will take longer to roll out.
Mr Ó Cathasaigh said he did not believe a no vote from the Green Party would result in a better deal at a later stage.
Green Party Councillor for Cork Lorna Bogue said that "it is on a knife edge" whether Green Party members will support the programme for government.
Speaking on RTÉ's Today with Sarah McInerney she said the goals within the party on health and housing are "not enough", and prevent her from supporting the document.
She said the agreement postpones Sláintecare for another two years and does not increase nurses' pay.
In relation to housing, she said the commitment of 50,000 social houses is not enough, and she highlighted that this is 10,000 fewer homes than what was included in the Fine Gael manifesto.
"This is more of the same and business as usual," she said.
On the same programme Green Party Councillor for Cork City South Central Dan Boyle said he believed equal consensus would have to be reached by all three parties at the cabinet table if the Greens entered into government.
He said he doesn't believe the "weight of any one party would be greater than the other".
Mr Boyle said: "Once you are in government you have an opportunity to bring about legislation that perhaps wasn't included in the original programme for government.
"It is a mission statement and it outlines goals and if properly worded as it is on the climate bill it gets the schedule and prioritises particular commitments."
Over the weekend, Green Party leader Eamon Ryan said he does not believe there is any wriggle room to renegotiate the programme for government, following calls from within his party to do so.
Meanwhile, Fianna Fáil TD John Lahart has said he will oppose going into government with Fine Gael and the Green Party.
He is the second party TD alongside Éamon Ó Cuív to declare that they will vote no in the ballot.
Mr Lahart said he was dissatisfied with several aspects of the programme for government, including housing policy and the absence of a feasibility study for a Metro South.
The Dublin South West TD told the Business Post that he was unhappy with the planned 18-month extension of the Strategic Housing Development, which allows developers to bypass local planners.
Mr Lahart also said Fianna Fáil should have spoken to other parties, including Sinn Féin, about forming a government.
Former Fianna Fáil TD for Kerry John Brassil has also said he will vote no in the ballot because of the decision to halt plans for the Shannon LNG terminal.
Mr Brassil said he saw very little of the party's footprint in the programme for government and he did not envisage that Fianna Fáil's election manifesto would be delivered upon.
Fianna Fáil Councillors in South Dublin County Council have agreed to endorse the programme.
In a statement the councillors said: "The country needs a strong government now more than ever due to the impact of the pandemic, the subsequent lockdown of our economy and the uncertain global political landscape that exists."
The results of all three party votes will be announced on Friday.
All three must back the deal in order for Fianna Fáil leader Micheál Martin to be elected Taoiseach when the Dáil sits next Saturday.