Cameron said if the European Union becomes a "single currency club" then it would not be one for Britain. The country joined what was then the European Economic Community in 1973 but has remained removed from the heart of Europe under successive prime ministers. But he must be able to extract concessions from other countries and placate a strong euro-skeptic tide in Britain, without sparking resistance or triggering an accidental exit from the bloc.
Cameron also spoke to European Commission chief Jean-Claude Juncker by telephone on Tuesday, Schinas said. Cameron wants to discourage more from coming by limiting their access to social benefits for the first four years after they arrive.
The negotiation over Britain's demands will also be a crucial test for nations, starting with Germany and France, that are struggling to maintain cohesion and a sense of progress within the bloc after years in which economic stagnation, rising populism and assertive nationalism have undercut their plans to bind the Continent's governments and people more closely together.
"I have great difficulty in relation to the list of demands that are being made because all of them - nearly without exception - require treaty change and you can not get treaty change without the agreement of the member states", he said.
However, in a speech on the same day he undermined this position, declaring: "I'm open to different ways of dealing with this issue".
He told HMS Bulwark's crew: "We need to smash those gangs and that is what the next stage of this work is going to be about".
Mr. Cameron's speech also drew a number of detractors within his own party, receiving little support from those anti-EU lawmakers in his Conservative Party he was aiming to placate when he first promised a referendum on membership in 2013.
Exemption from forming an "ever closer union" should be easy as the notion itself is widely considered outdated.
His demands were met with ridicule by a few Conservative Eurosceptics, with backbencher Bernard Jenkin stunning MPs by saying: "Is that it?"
Most contentiously, Cameron said Britain wants to "control migration from the European Union".
A deal may not be finalised at next month's summit in Brussels, but the odds are that Cameron will achieve most of what he is looking for and will lead the campaign for Britain to remain in the EU.
The Czech Republic will insist on preserving the free movement of people and same rights for all European Union citizens, Prime Minister Bohuslav Sobotka said today in reaction to European Union reforms proposed by Britain.
A Downing Street spokeswoman said: "It's an informal council and so we don't expect decisions to be taken".
German chancellor Angela Merkel thought there were "some hard [demands], others that are less difficult" while stressing she was "reasonably confident" of a deal. The European Union has a record of solving intractable problems.
This changed when YouGov asked the same voters what they would do if "the British government under David Cameron renegotiated our relationship with Europe and said that Britain's interests were now protected".
Yet even although Cameron "has set the bar very low, he is still going to trip over it", says Peter Oborne in the Daily Mail.
He specifically latched on to proposals where freedom of movement would be limited by allowing the U.K.to restrict benefits for migrants from other member states.