Pro-EU party wins, cuts British premier’s Parliament margin to just 1

LONDON — British Prime Minister Boris Johnson’s Brexit-backing Conservative Party lost a special election Friday to a pro-EU opposition candidate, leaving Johnson with only a one-vote majority in Parliament as the United Kingdom’s departure from the European Union looms.

In the Conservatives’ first electoral test since Johnson became prime minister last month on a vow to complete Brexit “do or die,” the party was defeated for the seat of Brecon and Radnorshire in Wales by Jane Dodds of the Liberal Democrats. Dodds won 43% of the vote, against 39% for Conservative Chris Davies, who fought to retain the seat after being convicted and fined for expenses fraud.

Dodds urged the prime minister to rule out leaving the EU without a divorce agreement, saying “a no-deal Brexit would be a disaster” for agricultural areas like her constituency some 175 miles west of London.

Sheep farmers in Wales worry that, without a Brexit deal, steep tariffs on lamb exports will devastate their business.

Johnson won a Conservative Party leadership race by vowing that Britain will leave the European Union on Oct. 31, with or without a divorce deal. But he faces opposition from Parliament, and the by-election result makes it even harder for the government to pass laws and win votes in the 90 days before the Brexit deadline.

The outcome also reflects the seismic effect Britain’s decision three years ago to leave the 28-nation EU has had on the country’s politics, with voters increasingly split into pro-Brexit and pro-EU camps.

The centrist Liberal Democrats have seen their support surge because of their call for Britain to remain in the bloc. In European Parliament elections in May, the party took 20% of votes, trouncing both the Conservatives and the main opposition Labor...