Taoiseach Bertie Ahern is due to attend the European Council meeting in Brussels today.
Mr Ahern, who will be accompanied by Minister for Foreign Affairs Dermot Ahern and Minister of State for European Affairs Dick Roche, said the meeting would welcome yesterday's signing of the Reform Treaty.
He warned yesterday that Ireland would "cut ourselves apart" from the European Union if there is a No vote in next year's referendum in Ireland on the treaty.
The document was signed together in Lisbon yesterday by 26 of the 27 EU leaders. British prime minister Gordon Brown arrived late and signed it alone.
The treaty must be ratified by all member states by January 2009.
Denmark, one of the EU's most Eurosceptic states, has already decided that it does not need to hold a referendum. Portugal has yet to decide.
The Government has yet to settle on a date for a referendum here, partly because it does not yet know if an all-party agreement on the wording for a children's rights referendum can be reached. Mr Ahern favours running both votes on the same day.
The Oireachtas European Affairs Committee announced yesterday it is to hold public information meetings around the country on the treaty before a referendum takes place.
If passed, the treaty would simplify EU decision-making in the club of 27, make qualified majority voting more common and lead to the appointment of an EU president.
The European Commission would win powers to set up EU initiatives on crime, terrorism and other issues, although Ireland has opted out, for now, of letting Brussels take the lead on judicial co-operation.