Independent Alliance member John Halligan has pulled out of government formation talks, saying he will not back Enda Kenny or Micheal Martin's bids to become Taoiseach,
.The Waterford TD confirmed the move to the five other Alliance members, Fine Gael and Fianna Fáil last night.
It is understood Mr Halligan pulled out of talks due to the fact neither party has as yet said they will restore 24-hour cardiac cover at Waterford Regional Hospital.
I can play no part in forming a government until this intolerable situation is resolved.
— John Halligan (@JohnHalligan) April 12, 2016
However, there are some suggestions that the move is a negotiation tactic designed to ensure the hospital policy is included in any Programme for Government, and that Mr Halligan may return, should this be agreed.
While the Waterford hospital service is an issue that directly affects his own constituency, the long-time TD is adamant it is not a parish pump problem and impacts on the entire south-east region.
It is also believed that other Independent Alliance members back him in his view that the unit should be included in any deal with either party.
Mr Halligan's decision to leave talks was widely expected to happen in recent days, with Fine Gael ministers privately saying last week they believed only five of the Alliance were realistic partners for a potential minority government.
The Alliance had met with Fine Gael negotiator Simon Coveney and junior minister Simon Harris last night to seek an update on talks after a six-hour internal meeting, after which Mr Halligan is believed to have let his decision be known.
The situation is unlikely to split the Alliance, with the five remaining members - Finian McGrath, Shane Ross, Sean Canney, Kevin 'Boxer' Moran and Michael Fitzmaurice - believed to still be working as a joint group.
However, the separate five-strong rural TDs group is facing an altogether more complex problem, with a clear division now emerging.
Members Mattie McGrath and Noel Grealish - ex Fianna Fáil and Progressive Democrat TDs respectively - are believed to favour backing Micheál Martin.
But colleague Denis Naughten - an ex Fine Gael TD - wants to support Enda Kenny, with West Cork's Michael Collins and Clare's Dr Michael Harty undecided.
Fine Gael and Fianna Fáil are believed to be pressing all Independents to make their views known before tomorrow's Dáil Taoiseach nomination vote - should it take place.
However, Independents have repeatedly said they will not make their positions clear until the parties outline exactly what they are voting for and how each version of a minority government would work.
It is believed the separate Healy-Rae brothers' group is in constant contact with a senior Fine Gael minister who is a member of the party's negotiating team.
Michael Healy-Rae would last night not be drawn on whether he is the Independent TD rumoured to have been offered a ministerial role if he gives his vote to Mr Kenny.