BRUSSELS, Belgium — The leaders of 25 current and imminent members of the European Union failed to reach agreement on Saturday on a draft constitution, stumbling on a problem familiar to Americans: how to apportion power among large and small states.
At issue was a proposal to discard a voting system agreed upon three years ago that gave Spain, a member of the union, and Poland, which joins next year, almost as much voting weight each as Germany, which has more than twice the population of either.
Klaus Hansch, a German deputy of the European Parliament, laid the blame for the failed meeting squarely on the two nations' unwillingness to compromise. "I hope that Spain and Poland realize that the failure of the summit is due to them and that they missed a historic opportunity," he said.
But Italy's prime minister, Silvio Berlusconi, chairman of the talks, defended the Poles. Entering the talks Saturday morning, he told reporters that on Friday he had circulated four different voting formulas among the leaders.
"You cannot make Spain and Poland responsible for an eventual failure," Berlusconi said. "They are open to other formulas."
Officially, the leaders said they would meet to try again next year. But the failure touched off bitter recriminations, notably between Germans and Poles, underscoring differences between current and imminent members of the union. The war in Iraq also played a part. The bitter divisions in "old" and "new" Europe over whether to go along with the United States' military action contributed to the wedges driving the leaders apart.
The failure prompted reports that some countries, most notably the six founders of the European Union — Germany, France, Italy, Belgium, Luxembourg and the Netherlands — would go it alone in efforts to integrate more closely in areas like foreign and defense policy.
Poland's prime minister, Leszek Miller, left Brussels and was expected to convene a Cabinet meeting to inform the government of the outcome, Polish diplomats said.
The meeting was not without its successes. On Friday, the leaders took a first important step toward striking a deal on the constitution's draft text, the subject of almost two years of discussion, when they agreed unanimously to a common defense policy that included planning abilities independent of NATO.
The constitution is considered crucial in light of the approaching enlargement, by which the union, which began as a customs union of just six countries, will become a 25-member club, bringing most of the former East Bloc states, including Poland, Hungary, the Czech Republic and Slovenia, into its embrace.