LONDON -- Britain's prime minister said Wednesday he will offer citizens a vote on whether to leave the European Union if his party wins the next election, prompting warnings from fellow member states about the soundness of such a move.
Claiming that public disillusionment with the 27-nation EU is "at an all-time high," David Cameron used a long-awaited speech in central London to say that the terms of Britain's membership in the bloc should be revised and the country's citizens should have a say.
Cameron proposed Wednesday that his Conservative Party renegotiate the U.K.'s relationship with the European Union if it wins the next general election, expected in 2015.
"Once that new settlement has been negotiated, we will give the British people a referendum with a very simple in or out choice to stay in the EU on these new terms. Or come out altogether," Cameron said. "It will be an in-out referendum."
EU member states, which in the run-up to the speech stressed the importance of Britain's presence in the bloc, took a sharper tone after Cameron spoke.
Martin Schulz, the president of the European Parliament, said Cameron was playing "a dangerous game," accusing him of trying to appease his increasingly anti-European Union Party and shore up support.
"This was an inward-looking speech that does not reflect European reality and will not impress many of the U.K.'s European partners," Schulz said. "The speech was more about domestic politics."
Much of the criticism directed at Cameron has accused him of trying an "a la carte" approach to membership in the bloc and seeking to play by some but not all of its rules.
French Foreign Minister Laurent Fabius warned Wednesday that a British withdrawal from the EU would be dangerous for both the bloc and Britain.
"Say that Europe is a soccer club. You join this soccer club, but you can't say you want to play rugby," he told France-Info radio.
German Foreign Minister Guido Westerwelle said his country wants Britain "to remain an active and constructive part of the European Union."
He would not say if he would rule out renegotiating terms with Britain, but he suggested that countries could not be allowed to write their own terms for EU membership, saying "a policy of cherry-picking won't function."
Cameron stressed that his first priority is renegotiating the EU treaty -- not leaving the bloc.
"I say to our European partners, frustrated as some of them no doubt are by Britain's attitude: work with us on this," he said.
Membership of the EU has given the U.K. access to the massive joint European market as well as a say in how the region should govern itself and run its financial markets. The country has also benefited from EU funds to build infrastructure such as broadband networks.
Cameron insisted Wednesday that a "one size fits all" approach to the EU is misguided. Britain, a fiercely independent island nation, has always had a fraught relationship with the bloc. It benefits from the single market but is among 10 of the EU countries not to use the euro as its currency.
"Let us not be misled by the fallacy that a deep and workable single market requires everything to be harmonized, to hanker after some unattainable and infinitely level playing field," he said. "Countries are different. They make different choices. We cannot harmonize everything."
Even as he raised the specter of a referendum, Cameron reiterated his view that Britain should stay in the EU.
"I speak as British prime minister with a positive vision for the future of the European Union. A future in which Britain wants, and should want, to play a committed and active part," Cameron said. "There is no doubt that we are more powerful in Washington, in Beijing, in Delhi because we are a powerful player in the European Union."
He cautioned against holding a referendum immediately, saying it would be wrong to have the vote "before we have had a chance to put the relationship right" and before the euro zone emerges from its fiscal crisis.
The timeline Cameron laid out mostly hinges on a Conservative victory in the next general election. Still, Cameron said legislation will be drafted before 2015 so that if his party wins, it can be introduced and passed quickly enough to ensure a vote could be held "in the first half" of the next five-year Parliament.
The Conservatives formed a coalition government with the Liberal Democrats after an inconclusive 2010 election. Pegging the possibility of a vote to an electoral win could be a gamble to appease increasingly vocal Conservative euroskeptics and stem the stream of voters who have jumped ship to the UK Independence Party, which advocates EU withdrawal.