The Taoiseach, Mr Ahern, has acknowledged that the Government faces "difficulties" in efforts to retain its veto over taxation policy in the new European constitution.
He told the National Forum on Europe yesterday that not many other governments were taking the same stance on taxation. "We have few alliances, not many."
He insisted that the Government would fight to retain the veto and said he believed that the EU governments would "accommodate all major concerns". This would enable each government to say the final constitution accommodated its key interests, he said.
"We wish to see unanimity retained for all elements of taxation and for the criminal law aspects of justice and home affairs, both of which are areas of particular sensitivity."
Mr Ahern said the provisions on security and defence in the draft treaty agreed by the Convention on the Future of Europe required further work. "Our position is that we are not part and will not be part of a common defence unless the people decide to in a referendum," he said.
However, Fine Gael leader Mr Enda Kenny told the forum that the State's foreign and defence policy required radical change.
"We should become one of the architects of European defence rather than a spectator."
Mr Kenny said it was farcical that the Defence Forces could not participate in the EU mission in Macedonia because the force was not set up under a UN mandate.
Mr Ahern said he had a "slightly different view". He did not believe the "triple lock" mechanism - requiring a Government decision, a Dáil majority and a UN mandate to sanction Irish participation in a military action abroad - could be changed.
Mr Ahern said he supported the inclusion in the constitution of a reference to Europe's Christian heritage "as a matter of fact".
"If we can get a suitable form of words that does not bring division, well and good."
However, Labour TD Ms Liz McManus said the inclusion of such a reference would amount to "selling the people short".
She said there had been a pre-Christian phase in European history and said the modern EU states were influenced by the Jewish and Muslim religions and by those of no faith.
Mr Ahern said it should be remembered that the draft constitution "does not fundamentally change the relationship between the EU and its member-states".
The final document should be read in its entirety, he said. "It is simply not appropriate or honest to pick out some provision of the draft constitutional treaty and treat it in isolation from the articles that are linked to it.
"The great bulk of the draft constitutional treaty constitutes existing \ union law."
