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.
Foreign Secretary Philip Hammond has warned that the British people are likely vote to leave the EU unless there is substantial reform in Brussels.
He spoke as David Cameron began a whistlestop tour of Europe, meeting political leaders in a bid to build support for change.
ITV News deputy political editor Chris Ship reports:
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.