The independent TD Noel Grealish has pledged to give the government "necessary support" during the Brexit negotiations to strengthen the stability of the minority administration.
The TD of Galway West said that he had made the decision following a meeting with Tánaiste Simon Coveney and a long conversation with Taoiseach Leo Varadkar.
In a statement released Saturday night by the Taoiseach Ministry, Mr. Grealish said:
"Ireland is now entering one of the most critical and uncertain phases since the founding of our state, and it is in the best interest of our country as a whole to have a stable government at this crucial time."
"I've also talked to Fianna Fáil's leader, Micheál Martin, and I believe there is a compelling public interest that must be served at this time that outweighs the interests of any politician, whether alone or in concert."
The working majority of the government was threatened this week with the resignation of Denis Naughten as Secretary of Communications because of a controversy that has challenged the future of the national broadband plan.
The departure of Mr. Naughten from the government had reduced the number of votes that the Taoiseach in the Dáil can lead to 54 – three missing in the omission of Fianna Fáil a mere majority.
On Saturday, Sinn Féin's president, Mary Lou McDonald, said the government's loss of confidence and supply had taken its course and that Fine Gael and Fianna Fáil should form a coalition or make a choice.
In a statement, Ms. McDonald said, "Fianna Fáil and Fine Gael have made a decision to formalize their position as coalition partners in the government or to go to the people."
Under the current agreement, Fianna Fáil, the minority government made up of Fine Gael and Independents, undertook to provide three budgets and refrain from giving votes of no confidence.
Ms. McDonald said the trust-and-offer has "led to insecurity, instability and a worsening crisis".
"It was a political contra-job that would allow Fianna Fáil to pretend that she was in opposition while Fine Gael is acting without sanctions in the government," she said.
Mr. Martin and Mr. Varadkar will meet next week to discuss the future of the agreement. In a letter from Friday, Mr. Martin suggested that both commit to not collapse the government until a final Brexit settlement is reached.
In response, Varadkar said that a full renegotiation of the Trust-and-Supply Agreement with a commitment to make a summer 2020 election could be completed within a month.
"We are at a critical moment in our history as we face the challenge of Brexit, attacks on the Good Friday Agreement and the housing and health crisis," McDonald said.
"The country needs clarity, workable solutions and stability," she said.