The Labour Party could go into government with any other partner as long as it had "sufficient clout", the party leader, Mr Pat Rabbitte, said at the weekend.
He told the TEEU trade union conference in Galway that entering coalition should not be a matter of principle and it would be wrong to rule out negotiations.
After a conference delegate suggested Labour should not enter coalition again until it had become the second biggest political party in the State, Mr Rabbitte said he agreed that the party needed to acquire "critical mass".
"Then it doesn't matter who it's in government with, if it has that clout," he said.
The refusal of Mr Rabbitte's predecessor, Mr Ruairí Quinn, to rule out coalition with Fianna Fáil was considered by some to have cost the party support in the May general election. Mr Rabbitte, in contrast, had said he would not serve in a Fianna Fáil-led administration.
Asked if his comments to the TEEU conference meant he would be prepared to enter government with Fianna Fáil in the future, Mr Rabbitte said he had been answering "in principle" a question that had been put to him.
"It seems to me to be logical that unless Labour has critical mass, it's not in a position to seriously implement its own agenda. If you're asking me about the next election, that's probably four years away and whatever talent and energy I have will be devoted to replacing this Government.
"I'm not going to put myself in a position of saying what proposition I would put to the annual conference some three or four months in advance of a general election." Mr Rabbitte also told the conference he wanted to work towards "ever closer relations" between the Labour Party and the trade union movement. By this he meant the "development of a structured relationship based on the recognition that the party and the trade unions share a common purpose".
He also called for further reductions in Corporation Tax to be frozen. "I think the move towards 12.5 per cent is a valuable part of our industrial strategy, but in the context of the present difficult budget situation we have to ask can we not postpone achievement of the 12.5 per cent rate for at least a year."