U.K.’s Boris Johnson Pledges to Deliver Brexit With or Without a Deal

LONDON—Boris Johnson, the leading candidate to become the U.K.’s next prime minister, laid out his plan to take the country out of the European Union by Oct. 31, if necessary without a divorce deal to smooth Britain’s exit.

During a speech Wednesday launching his campaign, the former foreign secretary said he would seek to renegotiate Britain’s exit deal with the EU. At the same time, he would launch preparations across the country to weather a “no-deal” exit that many businesses and economists say would severely damage the...