Leaders of 25 present and future European Union states have drawn battle lines at the start of negotiations over a constitution that will establish a new ruling order in an enlarged EU.
Although the prime ministers and presidents agreed a new treaty was needed to ensure Europe's prosperity and influence, there were sharp differences about the balance of power.
As their foreign ministers began negotiating in earnest, a few hundred anti-globalisation protesters clashed with riot police within sight of the grandiose, marbled summit centre in the fascist-era Rome suburb of Eur.
Italian Prime Minister Silvio Berlusconi, whose country holds the rotating EU presidency, opened the one-day gathering on Saturday by warning leaders against putting national interests first.
"In a globalised world, Europe must rediscover its ancient leadership role, revitalising the roots of its civilisation," Berlusconi, who wants a deal by the end of the year, told reporters. "This will be no easy task."
The draft constitution proposes an overhaul of EU institutions to prevent paralysis after 10 new members join the 15-nation bloc next May, swelling the EU population to 450 million.
Backed by France and Germany, Italy is keen to stick as close as possible to the text drawn up by a Convention of EU lawmakers and delegates in June after 16 months of debate.
But the summit made clear many countries want changes, some radical, with smaller states worried their larger neighbours may steamroller them into a bad deal.
Spanish Prime Minister Jose Maria Aznar said the Convention had exceeded its mandate by trying to rewrite the voting rules for majority decision-making and warned he was not about to surrender.
"If you have got something to negotiate it is better to be feared," Aznar told reporters.
French President Jacques Chirac and German Chancellor Gerhard Schroeder hinted that countries blocking progress on the constitution might suffer when it came to handing out EU funds.
"Of course there's a link," both said in identical words.
Spain has been the biggest beneficiary of EU regional aid, but Aznar shrugged off any threat to future handouts.
"We are no longer a backward, lagging country as we were before. We are a prosperous country, and that has far-reaching consequences on how we approach these political questions."
Spain, backed by Poland, wants to keep a complex voting system agreed in 2000, which gave it power disproportionate to its population.
The Convention proposed a simpler system in which most decisions would be taken by a majority of member states representing at least 60 percent of the population.
But Italy conceded that unless there was a consensus for this reform, the Nice rules would remain in force.
The Convention suggested slimming down the executive European Commission to 15 full voting members from 20 at present and 25 next year. But this idea came under fire from smaller states which fear losing their voice in the new Europe.
Diplomats said at least half the leaders backed keeping one commissioner per member state and none explicitly opposed it, suggesting the Convention draft is likely to be amended.
The EU leaders issued a bland statement, saying the constitution represented "a vital step" towards making Europe "more efficient and closer to its citizens".