Prime Minister David Cameron on Thursday appealed to Germany to help him achieve the European Union reforms he needs to persuade Britons to remain in the 28-nation bloc.
Britain is expected to hold a referendum on whether to remain in the EU by the end of 2017, and Cameron is currently in Germany to renegotiate ties with the union to help counter burgeoning British euroscepticism.
"Support for our membership has declined over many years. So I am negotiating changes which will address the concerns of the British people," Cameron wrote in an article for Germany's Bild newspaper.
"But these changes will benefit the EU too, and Germany can help deliver them."
Cameron wants the EU to cut bureaucracy and shift more powers from Brussels to member states.
He is also seeking guarantees that Britain will be protected from closer EU political integration and from economic decisions made by the 19 EU members that use the euro currency.
Those demands have so far proven relatively uncontroversial.
However, a key sticking point for several EU members is Cameron's aim to restrict benefits for EU migrants for their first four years in Britain.
Critics of the plan say the measure would harm the EU's central tenets of non-discrimination between EU citizens and freedom of movement between member states.
While German Chancellor Angela Merkel is seen as generally supportive of Britain's position, she has stressed that "the fundamental achievements of European integration" are not up for debate.
"We want to stop people taking out from a welfare system without contributing to it first," Cameron wrote.
"Like Germany, Britain believes in the principle of free movement of workers. But that should not mean the current freedom to claim all benefits from day one and that's why I've proposed restricting this for the first four years."
Cameron is later expected to travel to Hungary for talks with Prime Minister Viktor Orban.
The British leader is keen to avoid a so-called "Brexit," but faces a large eurosceptic contingent within his Conservative party and growing public discontent over Britain's relationship with Brussels.
Highlighting divisions over the EU, Cameron on Tuesday said his ministers would be allowed to campaign for or against Britain's EU membership ahead of the referendum.