Prime Minister David Cameron promised on Thursday to speed up Britain's renegotiation of its ties with the European Union and lay out specific demands next month ahead of a referendum on whether to quit the bloc that is due before the end of 2017.
Cameron says his bid to recast Britain's relations with the bloc it joined in 1973 is "bloody hard work", but some EU diplomats have privately expressed frustration that Britain has failed to submit precise detail of its proposals.
With EU leaders grappling with a migration crisis, some officials have cautioned that an initial schedule that envisaged a deal being hashed out in December could slip, pushing back Britain's referendum until at least late 2016.
"The pace will now quicken and I'll be again setting out the four vital areas where we need change, laying down what those changes will be at the start of November," Cameron said as he arrived for a summit of EU leaders in Brussels.
"So we quicken the pace and quicken those negotiations in the run-up to the December Council," he said of the next summit, due on Dec. 17-18.
A British divorce would shake the Union to its core, ripping away its second largest economy and one of its top two military powers. Pro-Europeans warn an exit from the EU would hurt Britain's economy and could trigger the break up of the United Kingdom by prompting another Scottish independence vote.
Until Cameron has a deal he thinks is good enough to sell to the British public, his government is refusing to back either the domestic 'in' or 'out' campaigns which launched over the past few weeks.
TIME TO TANGO?
Cameron, who opposes any further transfer of sovereignty to the EU and says voters are unhappy with the current settlement,
wants a commitment that the goal of "ever closer union" in the EU treaty's preamble should not apply to Britain.
He also seeks protection of British financial interests outside the euro area, better regulation to promote competitiveness to create jobs and growth, and tighter welfare rules to reduce the incentives for migration within the EU.
He formally began his renegotiation with a brief summary of Britain's objectives to other leaders at a meeting in Brussels in June and European Council President Donald Tusk has said leaders will discuss the issue again in December.
Senior EU officials and diplomats said that a substantive political negotiation at December's summit will only be possible if Britain delivers clear, written proposals to Brussels and the 27 other national governments by early November.
"I can't say that huge progress has been achieved. I can't say that nothing has been achieved. But to tango it takes two," EU chief executive Jean-Claude Juncker said on the eve of a meeting with Cameron.
"And so we have to dance and our British friends have to dance."
But for the politicians, the choreography is delicate.
Sources close to the talks said Cameron appeared to hesitate for fear of provoking a backlash from Eurosceptics during his Conservative Party conference last week and is waiting for the Polish general election, being held on Oct. 25.
The biggest of the eastern states whose citizens form a large portion of EU immigrants to Britain, Poland and its former Communist neighbours have made clear they are very wary of Cameron's calls for limits on the freedom of Europeans to live and work anywhere in the bloc.
But Cameron cannot delay for too long. He wants to finish his renegotiation before major elections in Germany and France in 2017.
German Chancellor Angela Merkel said on Thursday she would work constructively with Britain but cautioned that there would be no haggling over the principle of free movement and the principle of non-discrimination.
Opinion polls suggest British voters are split, and crises in the EU over Greek debt and a surge of migrants may be turning some Britons against staying in the 28-nation bloc.
"I'm confident we can get a good deal for Britain, fix those things that need to be fixed and I'm confident that this process is well under way and making good progress," Cameron said.