Good progress made on EU negotiations, says David Cameron
David Cameron has insisted "good progress" has been made on his EU negotiations on the eve of crunch talks with state leaders in Brussels.
The Prime Minister spoke with European Council president Donald Tusk ahead of the summit, where he hopes to lock down agreement of his demands which could spark the start of the referendum campaign.
A Downing Street spokeswoman said: "They agreed that good progress had been made in all four areas of our renegotiation, and that the draft texts presented a good basis for agreement at tomorrow's European Council, subject to the satisfactory resolution of outstanding issues.
"They looked forward to continuing the discussion at their meeting ahead of the Council tomorrow afternoon."
Mr Cameron was boosted on Wednesday by German chancellor Angela Merkel's declaration that most of his demands were "justified and necessary", while French prime minister Manuel Valls said it would be a "shock" for Europe if the UK voted to leave the EU.
But Mr Tusk warned that there is "no guarantee" he will reach an agreement and there were issues which would be "difficult to overcome".
In a letter to EU leaders, Mr Tusk said the summit on Thursday and Friday "will be a crucial moment for the unity of our union and for the future of the United Kingdom's relations within Europe".
He said: "After my consultations in the last hours I have to state frankly: There is still no guarantee that we will reach an agreement. We differ on some political issues and I am fully aware that it will be difficult to overcome them."
But "there will not be a better time for a compromise", he said, adding: "It is our unity that gives us strength and we must not lose this. It would be a defeat both for the UK and the European Union, but a geopolitical victory for those who seek to divide us."
Mr Tusk said the aim was to reach a "legally binding and irreversible agreement which addresses UK concerns, while being satisfactory to all" and he hoped a deal would be done at the summit.
Agreement at the summit would allow an in/out referendum to be held as early as June and open the door for senior Eurosceptic Tories to join the campaign in favour of Brexit.
If he secures a deal Mr Cameron will return to the UK for a Cabinet meeting to agree a Government position - and he has told ministers that collective responsibility will then be suspended on the issue so that they can campaign for either side.
Among prominent figures yet to show their hand is London Mayor Boris Johnson, who was called to Number 10 for talks as the PM seeks to secure his support for the "remain" camp.
Mr Johnson remained tight-lipped on his stance as he emerged from the 40-minute discussion but senior sources said he would "make everything abundantly clear by the end of the week" if a deal was concluded by EU leaders.
They insisted he remained "genuinely conflicted" on the issue and rejected suggestions he was seeking to exploit the issue to maximise his chances of succeeding Mr Cameron as Conservative leader.
In a pre-summit speech to the German parliament, Mrs Merkel said the changes being sought by Mr Cameron were "far from being demands that are just for Britain" and that it was in her country's national interest for the UK to remain in the EU.
"They are also European demands and many of them are justified and necessary," she said.
"Germany will make its contribution so that a result that satisfies everyone can be achieved, if possible already at the summit beginning tomorrow," she went on.
"I am convinced that it is in our national interest for Great Britain to remain an active member in a strong and successful European Union."
Mr Valls told the French parliament that a Brexit would send shockwaves "that we have trouble imagining in terms of the consequences on Europe", but indicated that Mr Cameron would not be allowed to create a pick-and-choose EU.
"Europe should be a place of solidarity between states and we cannot choose 'a la carte' based on what suits us," he said.
"Europe is a whole that we can adapt, but we can't rework it only according to our particular interests, otherwise a line is crossed."
Alongside last-minute wrangling over the EU deal, Mr Cameron is also finalising new domestic legislation designed to assert the sovereignty of the UK Parliament.
The Prime Minister is expected to publish plans soon for the UK Supreme Court to act as a "constitutional longstop" to regulate the impact of EU law on the UK in a way already done in Germany.
It is one of several areas of concern set out by Mr Johnson, who has questioned whether it would be a "bazooka or popgun" in taking on European judges and bureaucrats.
Tory former attorney general Dominic Grieve has suggested any such move would be "pointless" as it could be overridden by the UK's treaty obligations.
Conservative MP John Baron complained of "poor" communication between Downing Street and party backbenchers over the issue - after a letter signed by 40 colleagues failed to secure an audience with the PM.
"We've been unsuccessful in obtaining that meeting so I haven't been privy to any discussions. Boris Johnson apparently has, I wish him well," he told BBC Radio 4's The World At One.