The president of the European council declared on Thursday that some of David Cameron's EU demands are "unacceptable", although he suggested that the prime minister still has a chance to win over European leaders.
Speaking ahead of a crucial European council meeting in Brussels, Donald Tusk said: "The consultations I have led with all member states show goodwill of all the parties involved but it doesn't change the fact that some parts of the British proposal seem unacceptable.
"However, if Prime Minister Cameron persuades us tonight that we can work together to find solutions regarding all four baskets then we will have real chance to strike a deal in February."
The prime minister will address all 27 European leaders with his plans to reform the UK's treaty with the EU for the first time over dinner on Thursday night.
He is hoping to convince European leaders to concede on certain areas. One of the key measures Cameron has pushed is to allow the UK to cut in-work benefits for EU citizens from outside the UK for four years, although he will be willing to hear from other leaders if they have suggestions to reduce European migration to Britain.
Cameron formally laid out his demands for EU reform last month in advance of the referendum that is set to be held in the UK before 2017. The four key ones are: to tackle abuses of freedom of movement; to remove the UK from the EU's goal of "ever closer union" while giving national parliaments more power; to protect the single market for Britain; to cut red tape and make the EU more competitive.
Siraj Datoo is a political reporter for BuzzFeed News and is based in London.
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