David Cameron's plans could unravel EU, says president He said the whole European project could fall apart if all member states only looked out for their own interests. "If every member state were able to cherry-pick those parts of existing policies that they most like, and opt out of those that they least like, the union in general, and the single market in particular, would soon unravel," he said. All member states can, and do, have particular requests and needs that are always taken into consideration as part of our deliberations. I do not expect any member state to seek to undermine the fundamentals of our co-operative system in Europe. Mr van Rompuy's intervention comes after Nick Clegg, the Liberal Democrat deputy Prime Minister, warned that Britain must not back out of Europe. This week, he dismissed plans for a referendum on the country's membership of the EU as "putting the cart before the horse." He argued against offering a referendum on Britain's membership of the EU and says that Britain should instead be exercising its leadership role in Europe. The deputy Prime Minister insists that he is "not frightened" of a public vote but says that such a suggestion is premature given the uncertainty surrounding plans to rewrite the Lisbon treaty to try to underpin the euro. Mr Cameron has already promised Conservative MPs that the party will fight the election on a "clear Eurosceptic position." He wants Britain to take a step back from Europe as the countries in the eurozone country make plans to join together in a "super-state" with closer political and financial integration. A poll yesterday showed that most Britons now want to leave Europe, with 51 per cent saying they would vote for an exit - in a marked hardening of eurosceptic attitudes.