Prime Minister David Cameron has served notice that Britain could leave the European Union if its concerns about its membership are not resolved.
Extracts from a speech that Mr Cameron was planning to make show that the Prime Minister intended to make clear that he wants the UK to play a "committed and active" part in the EU in future.
But he was also planning to warn that, if changes are not made to address the three key challenges of eurozone crisis, economic competitiveness and dramatically declining public support, "the danger is that Europe will fail and the British people will drift towards the exit".
But the extracts released by Downing Street did not reveal whether the Prime Minister intended to commit himself to an in/out referendum on British membership of the EU following the renegotiation of its terms which he has already said he plans to undertake after the 2015 general election.
The Prime Minister's reference to possible exit from the EU is his starkest warning yet of the consequence of failure to reform Europe, and echoes Chancellor George Osborne's comment to a German newspaper last week that "in order that we can remain in the European Union, the EU must change".
Mr Cameron's long-awaited speech in the Netherlands was dramatically postponed on Thursday night, after the Prime Minister decided he should stay in London to deal with the bloody fallout from the hostage crisis in Algeria.
The postponement - to a date yet to be fixed - is the latest mishap to befall the his attempt, several months in the planning, to spell out his vision for the future of Europe. First trailed as early as September, the speech has already been so delayed that Mr Cameron joked he was taking a "tantric" approach to it.
He prepared the ground for a public statement of his Europe policy by speaking to opposite numbers in Germany and Sweden in the Netherlands over the last few days, and discussed on Thursday night what he planned to say with French president Francois Hollande and US president Barack Obama.
Segments of the speech showed that he was intending to tell Europe's leaders that they have a "duty" to respond to the growing frustration of their people and to accept change to the way the EU operates. "More of the same" would condemn EU nations to "less competitiveness, less growth, fewer jobs", he argued.
According to the speech extracts, Mr Cameron was planning to use the address to set out what he termed 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".
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