March 04, 2016 Issue

London—Mayor Boris Johnson announces on February 21 that he will campaign for Britain to leave the European Union. Johnson is among the most popular Conservatives in Britain, so his declaration was a blow to Prime Minister David Cameron, who negotiated revised membership terms for Britain in the EU before calling for a referendum to take place on June 23. Polls suggest most Britons would vote to stay in the EU, but the margin is narrowing because of fears about the growing numbers of migrants and refugees, as well as criticism of how Europe has handled that crisis.