Supporters of the Vote Leave campaign cheer as they wait for Boris Johnson, the former mayor of London, during the first day of a nationwide bus tour to campaign for a so-called Brexit in Truro, U.K., on Wednesday, May 11, 2016. While online polls suggest the contest for the June 23 referendum is too close to call, less frequent telephone polling has put the "Remain" camp ahead. Photographer: Luke MacGregor/Bloomberg via Getty Images