Talks are continuing in Brussels today towards deciding the final shape of a new constitution for Europe.
The summit, which ends today, marks the start of months of talks on how to streamline the EU and avoid gridlock when 10 more member states join next May.
The initial round of talks yesterday centred on the size of the future European Commission and the role of a new EU "foreign minister".
The Minister for Foreign Affairs, Mr Cowen, who represented the Taoiseach at yesterday morning's session of the summit, said the mood of the meeting was constructive.
The small EU countries - especially the newcomers from central and eastern Europe - are determined to keep the current system and have one Commissionereach, to ensure their voice is heard in policy-making.
They fear being sidelined by the Big Five unless the Commission representstheir interests.
The idea of a new post of foreign minister is causing a power struggle too because some want the new figurehead to be based in the Commission while others say he or she should work primarily for EU government.
A draft constitution on the summit table calls for a smaller "eurocracy". It also recommends the new foreign minister should represent the EU as a whole on the world stage - dividing time between sitting in on Commission talksand liaising with governments.
Last night the summit - attended by leaders of all 25 present and future member states - switched to talks on the EU's defence role.