Liberal-Democrat Union, a pro-European party, won a seat in the House of Commons that Britain's Conservative Party hopes to retain in a by-election Thursday, Aug. 1 in the Welsh constituency of Brecon and Radnorshire . Thus, Boris Johnson finds himself with a majority of one voice.

This is a major setback for Theresa May's successor, who was facing a first election test as head of the British government. The Johnson government's parliamentary majority was already in support of the Northern Ireland Democratic Unionist Party (DUP), leaving Johnson under threat from rebel members of the Tories, including the goal exit from the United Kingdom of the European Union on October 31st, if necessary without a divorce agreement.

"Boris Johnson's dwindling majority makes it clear that he does not have a mandate to leave the EU without an agreement," Liberal-Democratic Union leader Jo Swinson told reporters that results in the night of Thursday 1st to Friday 2nd August.

"I will do everything in my power to stop Brexit and offer an alternative, a positive vision," she said in a statement. "We now have one more MP (13 in total, Ed) who will vote against Brexit in Parliament."

The election in Brecon, a rural area in the heart of Wales, was made necessary by the cancellation of the mandate of Conservative MP Chris Davies for falsifying expenses. Davies was again the Tories' candidate, believing he had made a mistake.

Liberal Democrat Jane Dodds won the election with 13,826 votes, ahead of Davies who won 12,401 votes, according to official results. The Brexit Party of Nigel Farage was third with 3,331 votes, the Labor Party fourth with 1,680 votes.

However, by adding the votes, the pro-Brexit parties are ahead of the pro-Europeans in Brecon. Like the country, the "yes" won in the referendum on the exit of the EU in 2016.

Other pro-Europe parties had decided not to run a candidate in the by-election in the hope of strengthening the chances of the Liberal-Democratic Union by bringing together the votes of the voters in favor of keeping the EU.

With Reuters and AFP