David Cameron is holding talks with the German Chancellor Angela Merkel in Berlin today - someone he needs to win over if he is to have any chance of pushing his EU reform plans through.
He is also due to meet the Polish Prime Minister today, as he wraps up his bid to renegotiate the terms of the UK's membership of the European Union with key leaders.
David Cameron has met with Polish Prime Minister Ewa Kopacz in Warsaw as he continues his tour of Europe to lay out his plans for renegotiating the terms of the UK's membership of the European Union.
They agreed on issues including making Europe more competitive by strengthening the single market, cutting back red tape, ensuring fairness between euro-ins and euro-outs and more subsidiarity, respecting the sovereignty of Member States, a Downing Street spokesperson said.
On immigration and welfare, Kopacz also welcomed Cameron's "commitment to respect the principle of free movement."
"They agreed that there were issues concerning the interaction between free movement and national welfare systems that should be discussed further, the spokesperson said.
The pair also discussed the situation in Eastern Ukraine and agreed that the EU's existing sanctions must remain in force until the Minsk agreements are fully implemented.
David Cameron has begun a whirlwind tour of Europe to discuss his terms for renegotiating the UK's membership of the EU with key leaders.
Prime Minister plans a whistle-stop charm offensive with EU leaders this week.
Details of the In/Out referendum will be presented to Parliament in a Bill this morning.