The leader of the Conservative Party has said he still wants a referendum on the Lisbon treaty.
Voters in Ireland have approved the treaty in a referendum, it was announced on Saturday.
Nearly all 27 EU member states have backed the treaty.
Poland is expected to approve it this week, while in the Czech Republic ratification is being delayed by a legal challenge.
Ahead of the Tory conference in Manchester, which begins on Monday, leader David Cameron said he is still committed to his policy of a referendum on the issue.
"As long as that treaty is being discussed and debated anywhere in Europe, we will keep fighting for that referendum," he told the BBC.
"And if those are the circumstances at the time of the next general election, we will hold that referendum, and I would ask the British people to vote 'No' to that treaty."
Former prime minister Tony Blair had promised a referendum on an earlier draft of the treaty, known as the European Constitution.
However, when Irish voters rejected it in June 2008 it was renegotiated and became the Lisbon treaty.
The British government then said a referendum was not necessary.
Cameron would not be drawn on whether or not he would press ahead with a referendum if the Tories win the next election and the treaty has already been approved by all member states and come into effect.
The Lisbon Treaty amends existing EU treaties, rather than re-founding the EU by replacing old texts with a single document, as proposed by the European Constitution.
It also creates a fulltime president of the European Council, replacing the system of rotating the presidency every six months.
Blair is thought to be a candidate for the new role.
