Obama arrives in UK with royal lunch, Brexit on the menu

"Obama is not an instinctive pro-European," said Ian Bond of the London-based Centre for European Reform think-tank. "He opposes Brexit because it risks creating more problems for America in Europe." Polls put the pro-EU and Brexit camps neck-and-neck among those who express a preference to vote, although there is a large pool of people who remain undecided. Obama's "focus is on how Brexit would affect Europe's ability to help America tackle international problems," said Bond.