Government hopes of coaxing unions back into pay talks could fall flat as politicians' "foolish statements" further anger workers, Fianna Fail has warned.
Party leader Micheal Martin said Kieran Mulvey, the industrial relations mediator appointed to smooth out hostilities, faces a tougher task than ever.
"The job gets more difficult for Kieran Mulvey when foolish statements emanate from the Government like, 'There's no job security now anymore'," Mr Martin said. "That is a red flag to a bull for the people you want to negotiate with.
"So the job for Kieran Mulvey has become more difficult, by pronouncements and leaks emanating from Government that I don't think are appropriate."
Earlier, Communications Minister Pat Rabbitte admitted Mr Mulvey's task was a challenging one. But he insisted it was not impossible.
The Government appointed the Labour Relations Commission chief executive to try to break the deadlock on Croke Park II, which was overwhelmingly rejected by unions.
Meanwhile, Mr Martin advised the Fine Gael-Labour coalition to ditch the "divide and conquer" tactics it used during the first round of negotiations last month.
He said his party disagreed with the way the Government approached the issue and urged it to re-engage with unions.
"I think it's a very traditional, old style approach of counting numbers and if the main unions are on one side, you could isolate others," he said at Fianna Fail's ard fheis in Dublin's RDS. "And I think frontline workers got isolated, particularly in the health sector, and the numbers didn't add up in the end.
"It was divide and conquer, it was a bit of bribery with the 300 million euro honey pot and buying off unions, and side deals, and there was threatening at the end. That didn't work either. I think they should go back to the negotiating table and negotiate in good faith a proper deal."