Prime Minister David Cameron on Wednesday promised to hold a referendum on Britain's membership of the European Union by the end of 2017, should his Conservative party be reelected, but also argued for staying in the bloc despite rising euroscepticism back home.
"I want the EU to be a success, and I want a relationship between Britain and the EU that keeps us in it," he said in a highly anticipated speech held in London after several delays. "I never want us to pull up the drawbridge and retreat from the world."
At the same time, he acknowledged that "public disillusionment with the EU is at an all-time high," pointing to competitiveness problems, the rigidity of EU rules, and public frustration over Brussels institutions and decisions - notably on austerity.
"A question mark over Britain's place in the EU ... is already there and ignoring it won't make it go away," he said. "I am in favour of a referendum. I believe in confronting this issue."
However, immediately posing the in-or-out question would be a mistake, Cameron said, arguing that a new EU is still being shaped - with lessons being applied from the eurozone debt crisis - and that Britons thus would not know what they're voting for yet.
Cameron said his party would instead ask voters for a new mandate in 2015 to "negotiate a new settlement with our European partners," aiming for a more competitive, more flexible, fairer EU with more democratic accountability and more national powers.
He said he would support EU treaty changes as part of that drive.
"I want a better deal for Britain ... When we have negotiated that new settlement, we will give the British people a referendum with a very simple in or out choice," he said. "We will ... hold this referendum within the first half of the next (five-year) parliament."
He called for "cool heads" to prevail, pointing to the economic advantages the EU single market brings and the influence EU membership gives Britain on the international diplomatic scene.
"If we left the EU, it would be a one-way ticket, not a return," he warned. "Decisions made in the EU would continue to have a profound effect on our country, but we would have lost all our remaining vetoes and our voice in those decisions."
He urged European partners to work on addressing concerns raised by Britain, criticizing "those who denounce new thinking as heresy." But some of his EU reform ideas are bound to prove unacceptable in Brussels, especially on repatriating powers back to capitals. The EU and Britain have had uneasy ties during the eurozone crisis, with Cameron repeatedly standing in the way of deals that other EU politicians heralded as key to solve the bloc's woes.
French Foreign Minister Laurent Fabius on Tuesday proclaimed that his country would "roll out the red carpet" to investors fleeing Britain if it decides to leave the EU, echoing an invitation last year by Cameron to companies doing business in France.
Fabius criticized Britain's "a la carte" approach to Europe in an interview with French radio.
"Let's say Europe is a football club ... Once you're in it, you cannot say 'Let's play rugby,'" he noted.
The speech - which was originally scheduled for last week in the Netherlands - but was postponed because of the Algerian hostage crisis - was likely to score points with the anti-EU faction within Cameron's party. But not with his government's coalition partners, the pro-European Liberal Democrats. And Cameron also faces headwinds from the centre-left opposition.
Labour Party leader Ed Miliband called him "a weak prime minister" who first opposed a yes-or-no referendum, but now favours it because "he has lost control of his party and is too weak to do what is right for the country."
He said Cameron would create uncertainty that would hurt Britain economically, arguing that the prime minister should focus on creating jobs and improving growth.