British Prime Minister David Cameron promised Wednesday that a vote will be held on Britain's membership in the European Union if his party wins the next election, in 2015.
Cameron said the British people should have a choice about whether to remain in the EU on the basis of a renegotiated settlement -- or to leave.
The referendum should not be held until it's clear how changes made after the crisis in the eurozone work out, he said, while giving a landmark speech on Europe.
But, he said, it is important to ask "difficult questions" about the future now. Otherwise, British people could "drift towards the exit" if Europe fails.
The key problems Europe faces are instability in the eurozone, a "crisis of European competitiveness as other nations across the world soar ahead," and a lack of democratic accountability, Cameron said.
"There is a gap between the EU and its citizens which has grown dramatically in recent years," he said.
As a result, "democratic consent for the EU in Britain is now wafer thin," he said, and public disillusionment is at an all-time high.
"It is time to settle this European question in British politics," he said. "I say to the British people: This will be your decision."
The British prime minister insisted that he is not an isolationist, saying he would like Britain to remain part of Europe on the right terms, with the single market and competitiveness at the heart of the relationship.
And he set out a vision for an "updated" European Union that is "more flexible, more adaptable, more open, fit for the challenges of the modern age" -- and said all options should be on the table to negotiate a new deal.