Update 12.30pm: Former Labour strategist Fergus Finlay has warned Labour against going back into government, saying to do so now would do irreparable damage to the party.
Labour are currently considering supporting Fine Gael as part of a minority administration.
Mr Finlay said: "I think it would be appalling. I do not object to the notion of Labour supporting from the outside. They should be in the position of supporting what they can and criticising what they have to.
"But Labour has no mandate. If they were to go into government now, it would split the party down the middle."
Labour TD Willie Penrose has said the party has no mandate to go back into government.
Deputy Penrose said the party was soundly rejected by the electorate and is still "battered and bruised" after February's vote.
Fine Gael are trying to convince Labour to join them in a minority government with Independents.
However, Mr Penrose said he did not think party members would support the move.
"I don’t believe there's a mandate for Labour to go back into government," he said.
"We went to the country on the basis of an agreed form of government with Fine Gael and it was roundly rejected.
"We suffered a significant defeat in that election and were still battered and bruised, to be honest with you."