By Laurence Peter
BBC News, Brussels
Try as they might to talk about other pressing issues, EU leaders kept bumping into the elephant in the room - the Lisbon Treaty.
Mr Barroso (R) said ministers had not signed the treaty "just for fun"
Last year's German triumph in clinching the reform treaty after some eight years of institutional wrangling now looks like a pyrrhic victory.
The Irish No vote on Lisbon dominated the Brussels summit, with new cracks appearing just when EU leaders thought they had papered them over.
In a surprise announcement after the talks, UK Prime Minister Gordon Brown said full British ratification would have to wait until a court ruling on a Euro-sceptic millionaire's demand for a referendum on Lisbon.
The summit conclusions meanwhile noted - in a footnote - that ratification in the Czech Republic would not be complete until the country's constitutional court made a ruling on the treaty.
The 27-nation EU will return to the Lisbon stumbling block in October - by which time Irish leaders will need to have mapped out a way forward, based on detailed analysis of Irish anxieties about the treaty.
Does no mean no?
Lisbon is designed to reshape EU institutions to ease decision-making in the enlarged bloc.
German Chancellor Angela Merkel said she agreed with French President Nicolas Sarkozy that without Lisbon, further enlargement could not proceed. And Commission President Jose Manuel Barroso said the 27 countries were legally obliged to ratify the treaty - the governments had not signed up to it "just for fun".
But the leaders avoided answering the question: would the Irish be asked to vote again?
The Nice Treaty - the current mechanism for EU business - did get through in Ireland on a referendum re-run. But when asked whether this time "no means no", Mr Sarkozy replied cryptically that "no means no, but we are trying to make this an opportunity - it's what you call English pragmatism".
France will now team up with the Czechs and Swedes - holders of the EU presidency next year - to "manage" the treaty ratification, Mr Sarkozy said.
Danish politician Jens-Peter Bonde, a leading campaigner for a more transparent EU, told the BBC that the leaders had failed to discuss how to bring the EU's institutions closer to the people.
He expects the EU to draft a "package" in the coming months to address Irish concerns. But he says the EU ought to have a slimmed-down treaty, comprehensible to all, and put it to the popular vote in all 27 states.
Leaders seeking unity
The EU cannot afford another protracted round of institutional wrangling - not only because that is bad for its image, but also because of the European Parliament elections in a year's time.
Kirsty Hughes, an EU affairs expert, says "the Commission has a problem trying to pretend it's business as usual".
Yet that most definitely was Mr Barroso's message, reminding everyone that EU citizens are really concerned about the surge in food and fuel prices - and expect EU leaders to deliver. Citizens need an EU "bridge over troubled water", he said.
The 27 delegations agreed that France - the incoming EU president - would examine with the Commission various ways of easing the impact of the high fuel prices and present recommendations at the next summit.
Mr Sarkozy presented that as an "innovation" in the EU, describing it as a deal he had made with Chancellor Merkel. His call for an EU-wide cap on the VAT on fuel has had a mixed reception - and Germany takes a different view on oil prices.
As if to emphasise that the Lisbon wrangling would not block EU enlargement, the summit conclusions had plenty of comforting words for the Western Balkans states aspiring to join the bloc.
The leaders' statement deplored the violence in the run-up to Zimbabwe's second round of presidential elections on 27 June, saying they were "deeply concerned" and ready to take further measures against the perpetrators of violence. The UK government had pushed hard for a tough message on the abuses in Zimbabwe.
In contrast, the EU lifted sanctions on Cuba - a move the EU's Slovenian presidency described as "an encouraging message".
Bruised by the Irish No vote they may be, but EU leaders are striving to show more unity on the international stage.