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Lawyer and lawmaker Keir Starmer was elected leader of Britain's main opposition Labour Party on Saturday by a decisive margin, after a contest thrown into turmoil by the coronavirus outbreak.

A special conference to announce the winner was scrapped when the nation went into lockdown, and the news came in a press release accompanied by a pre-recorded acceptance speech.

Starmer, 57, comes from Labour's center-left wing, and his election marks a shift from the more strongly socialist course set by his predecessor, Jeremy Corbyn.

Starmer acknowledged that he was becoming leader of the opposition "at a moment like none other in our lifetime" and promised to "engage constructively" with the Conservative government to fight the coronavirus pandemic.

It’s the honour and privilege of my life to be elected as Leader of the Labour Party.



I will lead this great party into a new era, with confidence and hope, so that when the time comes, we can serve our country again – in government. pic.twitter.com/F4X088FTYY — Keir Starmer (@Keir_Starmer) April 4, 2020

The party said Starmer won on the first round of voting with 56.2 percent of all the votes cast, well ahead of rivals Rebecca Long-Bailey and Lisa Nandy. Angela Rayner was chosen as deputy leader in a vote of Labour's half a million members.

A former U.K. chief prosecutor named after Labour Party co-founder Keir Hardie, Starmer faces the challenge of reuniting a party deeply divided over the policies and legacy of Corbyn, The outgoing leader was elected party chief in 2015 on a wave of grassroots enthusiasm, and took Labour sharply to the left, proposing the nationalization of major industries and a huge increase in public spending.

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Corbyn also faced allegations that he had allowed anti-Semitism to fester in the party. He is a longtime supporter of the Palestinians and critic of Israel.

Starmer said "anti-Semitism has been a stain on our party."

"On behalf of the Labour Party, I am sorry, and I will tear out this poison by its roots," he said.

Corbyn drew thousands of new activists to the party, but lost two successive elections in 2017 and 2019. In December's election, Labour suffered its worst result since 1935, as the Conservatives won in working-class areas that had voted Labour for decades.

Labour has now been out of office for a decade that has brought the country three Conservative prime ministers - David Cameron, Theresa May and Boris Johnson.

Starmer said the party had "a mountain to climb" before it could return to government.

His election was welcomed by Labour moderates such as London Mayor Sadiq Khan, who said he was "delighted." But the Corbyn-supporting grassroots group Momentum said it would hold Starmer to account. It said "his mandate is to build on Jeremy's transformative vision."

Starmer has been the party's spokesman on Brexit, the issue that has consumed British politics for four years. But the country's departure from the European Union, which became official Jan. 31, has been pushed into the background by the coronavirus pandemic sweeping the globe.

Starmer faces a delicate challenge: How to hold the government to account during a national emergency while also supporting the fight against the virus.

Johnson announced Saturday that he was inviting leaders of opposition parties to a briefing with him and the government's top medical and scientific advisers on the fight against COVID-19.

"As party leaders, we have a duty to work together at this time of national emergency," Johnson wrote.

Starmer said he would not engage in "opposition for opposition's sake" but would criticize the government when necessary.

"We will shine a torch on critical issues and where we see mistakes or faltering government or things not happening as quickly as they should we'll challenge that and call that out," he said.