LLANELWEDD, Wales (Reuters) - Britain’s pro-European Union Liberal Democrats won a parliamentary seat from the governing Conservative Party, taking new Prime Minister Boris Johnson’s working majority to just one as he tries to steer the country through Brexit.

Johnson is expected to face a showdown with lawmakers in the autumn over his vow to take Britain out of the European Union on Oct. 31 with or without a divorce deal.

His government already relies on the support of a small Northern Irish party to pass legislation, with only a few rebels in his own Conservative Party needed to lose key votes.

The Liberal Democrats, who are calling for a second referendum on EU membership, won the Welsh seat of Brecon and Radnorshire with a majority of 1,425 votes.

“Boris Johnson’s shrinking majority makes it clear that he has no mandate to crash us out of the EU,” said Liberal Democrat leader Jo Swinson, whose party now have 13 seats in parliament.

A narrow majority of voters in the area had supported leaving the EU in the 2016 referendum and Swinson said the result showed her party could win in Brexit-supporting areas.

Wales, and the Brecon area, is a region where sheep outnumber people and where the prospect of steep EU tariffs being slapped on Welsh lamb exports in a no-deal Brexit have prompted widespread concern among farmers.

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The Brecon vote was called after Conservative lawmaker Chris Davies was ousted by a petition of constituents after being convicted of falsifying expenses. Liberal Democrat candidate Jane Dodds won with 13,826 votes.

Davies, who ran again for the Conservatives, came second with 12,401 votes. The Brexit Party came third with 3,331 votes, while the Labour Party came fourth on 1,680 votes, a bad result for the main opposition party with its vote share down 12 percent from 2017.

ELECTION?

The Liberal Democrats had held the seat from 1997 until 2015, when it was won by Davies. In the 2017 snap election he held the seat with a majority of just over 8,000 votes.

Johnson, who took office last week, has said he does not plan to hold an election before Britain leaves the EU but could be forced to if lawmakers try to stop him pursuing a no-deal exit by collapsing the government in a no confidence vote.

Some Conservative lawmakers have hinted they would vote against the government to thwart a no-deal Brexit. Party chairman James Cleverly said it was incumbent upon them to support Johnson.

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“This is the long-standing Conservative Party policy, the party policy we were all elected on which is to seek a deal from the European Union, but if that is not forthcoming, then to leave the European Union whatever,” Cleverly told BBC radio.

The result in Brecon, where the combined vote for pro-leave parties outnumbered pro-remain, would likely add to calls for a possible Conservative-Brexit Party alliance in any election.

Pro-EU parties, including the Greens and Plaid Cymru, agreed not to stand in the Brecon election on Thursday to boost the Liberal Democrats chances by concentrating the support of ‘Remain’ voters behind one candidate.

Swinson said it was likely the parties would seek similar agreements in any future parliamentary election.

The Brexit Party, led by prominent Brexit campaigner Nigel Farage, was only launched in April and rode a wave of anger over the government’s failure to deliver Brexit to sweep to victory in the United Kingdom’s European Parliament election in May.