The Government's representative at the Convention on the Future of Europe, Mr Ray MacSharry, has suggested that the body is unlikely to make significant changes to the European Union.
Speaking in Brussels after the Convention's third session, Mr MacSharry poured scorn on advocates of "grandiose" agendas for change.
"People talk with their heads in the clouds about a United States of Europe . . . Does anybody really think that in the next six months there will be any giant step?" he said.
Earlier, Mr MacSharry told the Convention that he opposed any significant expansion of the EU's areas of responsibility.
But he also rejected calls for responsibilities in some policy areas to be returned from Brussels to member-state governments.
"I don't believe that a convincing case has been made for rolling back any of the core competences and activities of the Union, including in such areas as agriculture, competition policy and regional policy.
"It would be a retrograde step were we to seek to dismantle some of the Union's most significant achievements," he said.
Mr MacSharry said that, instead of drawing up a new catalogue of competences, the EU should apply more assiduously the principle of subsidiarity, under which decisions should be taken at the lowest appropriate level.
In his contribution to the Convention, the Dublin Labour TD and MEP, Mr Proinsias de Rossa, criticised the Government's approach as excessively cautious.
"We need to be ambitious for Europe, ambitious for the way in which it can serve the peoples of Europe," he said. Stressing that he was speaking as a member of the Labour Party rather than a representative of all Irish parliamentarians, Mr de Rossa said that economic globalisation had created a need for Europe to do more.
"Europe needs to have the competence to protect the peoples of Europe from the transnational corporations.
"We need to have, at European level, the competence to ensure that people everywhere in Europe receive the social and caring support that they need. And having put in place the single currency we now have to address seriously the questions of economic governance, and inevitably we must therefore seek to guarantee decent social security and social rights, right across Europe," he said.
Yesterday's session revealed marked differences among Convention members over the EU's future role, with some calling for more integration while others suggested that Europe was already doing too much.
The Dutch government's representative, Mr Hans van Mierlo, said that the EU should take more joint action to defend human rights and promote democracy throughout the world and adopt a united position on asylum and immigration.
But the prime minister of the German state of Baden-Wuerttemberg, Mr Erwin Teufel, said such policy areas as the conservation of nature should be returned to national and regional governments.
Mr Gianfranco Fini, leader of the far-right Italian party, Alleanza Nazionale - which is allied to Fianna Fáil in the European parliament - called for a number of policy areas to be returned to national governments.