David Cameron and Angela Merkel exchange pained glances in Brussels tonight as the Prime Minister battles to rescue his EU renegotiation.
EU leaders will use a crunch summit dinner tonight to tell Mr Cameron that his call for a four-year ban on migrants claiming benefits is dead in the water.
Mrs Merkel has night warned she will not allow 'discrimination' against migrants but Mr Cameron insisted he was looking for 'real progress' on Britain's renegotiation goals from his fellow leaders.
David Cameron and Angela Merkel exchange pained glances in Brussels tonight as the Prime Minister battles to rescue his EU renegotiation
Mr Cameron has vowed to 'get the best deal for Britain' but appears unlikely to secure an agreement before the next EU summit in February.
The Tories promised to renegotiate Britain's membership of the EU before holding an in-out referendum by the end of 2017.
If a deal can be sealed by February at the latest, Mr Cameron would like to stage a snap vote in June.
Talks with other EU leaders have progressed well on curbing red-tape, protecting the UK from the eurozone and ending the idea of 'ever closer union' between member states.
But Mr Cameron faces an uphill battle on his key demand for a ban on migrants claiming in-work benefits for four years.
A number of eastern European states have made clear they do not see 'eye to eye' with the Prime Minister and will veto such a plan as discriminatory and in breach of the EU principle of free movement of labour.
And Labour leader Jeremy Corbyn also indicated opposition to the plan - a position not in line with his party's policy.
In Brussels, at a meeting of European Socialists, he told Politico: ‘If someone is working, paying taxes like anyone else, he should have access to the same benefits as everyone else.'
David Cameron, pictured in Brussels today, faces one of the biggest tests of his premiership tonight as he struggles to rescue his bid to keep Britain in the European Union
Should the UK remain a member of the European Union or leave the European Union?
Arriving at the summit, Mr Cameron said: 'Today is the day that our referendum bill received Royal assent so as a result our in/out referendum will be going ahead before the end of 2017.
'Now tonight here in Brussels we're going to have a conversation dedicated to Britain's renegotiation of its position in Europe and I want to see real progress in all of the four areas that I've mentioned.
'We're not pushing for a deal tonight but we're pushing for real momentum so that we can get this deal done.
'So I am going to be battling hard for Britain right through the night and I'll think we'll be getting a good deal.'
Addressing the Bundestag last night, Mrs Merkel described Britain as a 'natural ally' and stressed the 'enormous importance' of avoiding so-called 'Brexit'. But she made clear that Berlin was not prepared to give way on all Mr Cameron's demands.
'We don't want to, and we won't, call into question the core principles of European integration,' she said. 'These include in particular the principle of free movement and the principle of non-discrimination between European citizens.'
Her comments appeared to categorically rule out agreement for Mr Cameron's contentious plan to ban migrants from receiving in-work benefits for the first four years they are in the UK.
European Commission President Jean-Claude Juncker (right) insisted he is 'quite convinced we'll find an answer to that highly complicated question' of tackling migration. Martin Schulz, the President of the European Parliament, (left) said there remained 'enormous scepticism' about the four-year benefits ban.