The Social Democrats will not be part of the next government, deputy leader Cian O'Callaghan has said.
Speaking after a meeting of the parliamentary party, Mr O'Callaghan said that Fianna Fáil and Fine Gael were not committed to the Social Democrat's red-line issues.
These include the provision of 50,000 affordable homes, the full implementation of Sláintecare, a senior minister for disability, publicly funded childcare and significant action on climate change.
Mr O'Callaghan said he believes that a government led by Fianna Fáil and Fine Gael will most likely be supported by a number of independent TDs.
He said that while he believes the talks with the two parties have come to an end, the Social Democrats is available for further discussions if needed.
Meanwhile, formal invites to participate in talks on government formation are set to be issued in the coming days to the Regional Independent Group along with Independent TDs Michael and Danny Healy-Rae.
As the pace of negations quickens, the groups most likely to support Fianna Fáil and Fine Gael are preparing for detailed discussions.
A structure has been agreed among the two bigger parties to enable this to happen.
Seven Regional Independent TDs have vowed that they will act as a cohesive unit in the talks.
They are Michael Lowry, Noel Grealish, Sean Canney, Marian Harkin, Kevin 'Boxer' Moran, Barry Heneghan and Gillian Toole.
Independent Kerry TDs Michael and Danny Healy-Rae are also expected to open formal negotiations with Fianna Fáil and Fine Gael soon.
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Govt formation deadline 'tight' but possible - Harris
Fine Gael leader Simon Harris said he believes the deadline of 22 January to form the next government is possible, if "a little bit tight".
He was speaking at the official opening of a special school in Naas, Co Kildare, where he was asked about ongoing meetings between his party and Fianna Fáil.
Mr Harris said that he was in daily contact with Fianna Fáil leader Micheál Martin, sometimes several times a day, and that he believed they would have a new government within eight weeks, maybe less, of the General Election.
The Fine Gael leader said the two parties spoke about climate issues yesterday, discussions which would continue, and said that disability and justice were on the agenda today.
Three pillars of work are under way, Mr Harris added, namely policy, government structure and how any agreement is ratified by the two parties.
"I still think it's possible to meet the deadline of the 22nd, it's a little bit tight, but that's okay. People can work hard, work later, work longer. We're doing that and working through the weekend," he added.
Mr Harris said that Fine Gael had "good" engagement with the Social Democrats during government formation talks.
"I was at one meeting myself for a significant period of time, and then we had a further meeting with ... our negotiating team and their team," he said.
He also said that Fine Gael and Fianna Fáil intend to meet with Independent Ireland in the coming days too.
Additional reporting Juliette Gash
