'We believe the EU is stronger with the UK's involvement': Joe Biden to discuss referendum worries with David Cameron The US Vice President, Joe Biden, is in London today for a working lunch with David Cameron, on the last day of a tour of European capitals. Before his arrival in the UK last night, he repeated the US government's worry that David Cameron's promise of an in/out referendum could result in Britain leaving the EU. "We value our essential relationship with the UK, as well as our relationship with the EU, which makes critical contributions to peace, prosperity, and security in Europe and around the world," he told The Times. We believe the United Kingdom is stronger as a result of its membership. And we believe the EU is stronger with the UK's involvement. That's our view. He is also expected to discuss security in north Africa, the civil war in Syria, and Iran's nuclear programme. Mr Biden will have a spate meeting with Nick Clegg, at noon today, before going on to Downing Street. After lunch, he will sit in on a meeting of the National Security Council, before flying back to Washington. The Vice President's four day European tour began on Saturday, when he took part in a security conference in Munich. Yesterday he was in Paris for talks with the French President Francois Hollande.