Taoiseach Enda Kenny has branded Fianna Fail as "toxic" and "cynical", and claimed it should never again be trusted with the country's finances.
Mr Kenny launched a blistering attack on leader Michael Martin - just hours before the start of the opposition party's annual ard fheis in Dublin's RDS.
But the Taoiseach insisted he is not concerned about Fianna Fail's increasing popularity in the opinion polls, saying the current coalition will be judged based on the implementation of its Programme for Government.
"Voters are ultimately the masters in every election and the voters will have their opportunity to judge this Government in three years' time in 2016," he said.
"Their judgment will be based upon whether this Government has completed its Programme for Government, whether it has enacted its decisions in such a way that our public finances are in order, that our country is being run competently and efficiently, and that our Government has done their damnedest to deal with the devastation left behind by the previous administration."
Mr Kenny made the attack as he and Tanaiste Eamon Gilmore announced that the Government had delivered 96% of the measures so far in its Action Plan for Jobs.
He said the existing unemployment crisis was a result of Fianna Fail policies which had fuelled the property boom and left a generation saddled with massive debt.
"Fianna Fail's economic policies will never be forgotten by those families and communities hardest hit by their legacy," Mr Kenny added. "Not facing up to their responsibility for Ireland's economic crisis is just part of their opportunistic and cynical approach to politics which got us into this position in the first place."
Later, Mr Martin said he was shocked by the Taoiseach's "outburst". He said Mr Kenny's tirade was an attempt to deflect from the Government's "increasingly chaotic" approach to the major issues it faces.
"Today, we had hoped to hear some acknowledgement that his jobs plan simply isn't working and that he has recognised the need for a change in direction," Mr Martin said. "Instead, he took the opportunity at a jobs press conference to resort to old-style politics-as-usual. Of course, the irony of the leader of the Government of broken promises talking about 'trust' will not be lost on the Irish people."