By Zhang Bei, assistant research fellow, Department for European Studies, China Institute of International Studies

The United Kingdom’s renegotiations with its European Union membership has entered a critical juncture. Great Britain Prime Minister David Cameron has already proposed EU reforms in his speech at Chatham House, before delivering his letter to European Council President Donald Tusk.

A few days ago, British Chancellor George Osborne provided a detailed list of demands at a speech in Berlin, in preparation of the EU summit next week, in which the Brexit (UK potentially leaving the EU) issue would dominate the agenda.

Nevertheless, Cameron preferred to keep his demands in a low profile.

In earlier speeches, only general principles were put forward, such as the UK’s criticisms of an “ever closer Union” in the EU treaty that granted more powers for national parliaments, strengthening EU competitiveness, guarding the rights and interests of non-Euro countries.

Additionally, the EU sought further integration of member states, London wishes to cut benefits for EU immigrants..

Cameron wanted to make demands as general as possible to sell whatever he has achieved from renegotiations as a success story, to persuade voters to stay in the EU when they vote on the referendum next year.

His reversal on tactics shows pressure from both sides is mounting. The EU has complained the UK hasn’t put forward a concrete renegotiation checklist, despite holding weekly meetings for months between UK representatives and negotiators from Brussels, in which little was achieved.

While Eurosceptics in the Conservative party have made life more difficult for the PM, other high-profile Conservative Eurosceptics have interpreted the demands as mere trouble-making.

To quell Eurosceptics inside his party and to win concessions from the EU for a marginalized UK in the EU’s post-debt crisis governance, the referendum was put on agenda before the next UK Parliament elections.

Over the years, the PM has turned the story of a half-hearted member state demanding concessions from the EU, while reforming it with political dexterity, Cameron has made no missteps so far.

However, achieving his goals rely on the following months and the tasks ahead.

Time is limited for comprehensive renegotiations.

The timing has been bad. The EU has faced crisis after crisis, such as the Grexit (Greece potentially leaving the EU), which threatened the Euro Zone and after that a refugee crisis, which made many states, particularly Germany overwhelmed. Accordingly, the Brexit question was shelved.

As the referendum approaches, the Brexit issue is on the center stage now. Renegotiations are challenging but the UK holds several cards. The EU’s stance is defined by a multitude of opinions and interests of member states, successful renegotiations depends largely on whether the UK could find allies.

London is turning to Germany for cutting EU red tape, going to Nordic countries for defending the interests of non-Euro countries. London holds a tough position on EU immigrants and managed to get a few endorsements from EU countries. Yet such support may not help them later on.

The major challenge comes from the Conservative Party. Let’s assume he secured considerable concessions from the EU, Conservative Eurosceptics will still not accept that.

The Eurosceptic wing of his Party is becoming a stronger political force. Soon after the UK government’s balance of competences review had concluded the EU is not damaging the UK, Eurosceptics just shunned it.

The referendum results remain unpredictable. The Scottish independence referendum was a close call for unionists, even though they had expected to win by a large margin. A Brexit would brew a big storm, rewriting the European political landscapes.

From the beginning, the EU referendum and renegotiations are a big gamble. People hope all players will demonstrate wisdom and prudence in the following months ahead.