A Sinn Féin TD has said it will be impossible for the party to form a coalitiongovernment without the support of either Fianna Fail or Fine Gael.
Ireland's largest party Fianna Fail agreed not to go into coalition with SinnFéin following a four-hour meeting of its parliamentary party on Thursday.
The decision is likely to stop Sinn Féin entering power for the first time, astheir leader Mary Lou McDonald said forming a coalition without them or Fine Gael would be "very, very tricky".
Fine Gael and Fianna Fail have repeatedly ruled out going into government with Sinn Féin, as talks continue this week to try to form a coalition government.
Fianna Fail won the most seats with 38, but Sinn Féin won 37 seats and thehighest proportion of first preference votes following Saturday's generalelection.
Sinn Féin TD Eoin Ó Broin told RTÉ radio that Sinn Féin is still open to talking to all parties but said there are big policy differences between Sinn Féin and Fianna Fail.
He said: "On Tuesday morning the broad progressive left had 66 TDs and that is not enough for government."
"What we have been saying since then is we want a government led byprogressive left policies."
When asked how Sinn Féin can form a government without the two largest parties, he said: "You can't.
"The most irresponsible thing to do is what Micheal Martin has said - to sayhe won't talk to a party that now represents 24% of the electorate."
Fianna Fail leader Mr Martin told RTÉ news on Thursday that he would not rule out another general election.
He said: "In terms of the future, I can't be certain how all of this is goingto work. It will be very difficult.
"I would not rule out another general election. This is going to be sodifficult."
Mr Ó Broin criticised Mr Martin for ruling other parties in and out ofpotential government talks.
"If last week Micheal Martin was saying he wasn't going to talk to Fine Gaeland this week he saying he is, then very clearly Micheal Martin changes his mind on these matters."
A number of talks are continuing between the different parties on Friday.
Left wing party People Before Profit and Rise TD Paul Murphy will meet theGreen Party leader Eamon Ryan to try and form an alliance.