LONDON—Nearly a fifth of lawmakers in Prime Minister David Cameron’s Conservative Party threatened to block the government’s plans to introduce an emergency budget if the U.K. votes to leave the European Union next week. In a joint letter on Wednesday coordinated by the official group campaigning for Britain’s exit from the EU, the 57... The move marks the most serious challenge to his authority during the referendum campaign.

Source: Wall Street Journal June 15, 2016 12:04 UTC