Britain’s opposition Labour Party ruled Tuesday that its leader Jeremy Corbyn has the automatic right to stand in a new leadership contest, setting the stage for a struggle between the veteran socialist’s supporters and party lawmakers who want to oust him.

The turmoil engulfing the 116-year-old party, which governed Britain for 13 years until 2010 under Tony Blair and Gordon Brown, comes as the country’s political landscape is quickly changing following a June 23 vote to leave the European Union.

While the ruling Conservative Party has quickly appointed a new leader, Theresa May, to take over from Prime Minister David Cameron on Wednesday and pilot the Brexit process, Labour’s left-wing leadership is locked in a bitter internal power struggle with its more-moderate members of Parliament.

As Labour looks to define its priorities for the upcoming Brexit negotiations, party lawmaker Angela Eagle has challenged Corbyn to a leadership contest, saying he has failed to connect with voters and is not capable of winning a national election.

But Corbyn’s chances of maintaining control won a boost when Labour’s National Executive Committee (NEC) ruled that he should automatically appear on the ballot paper rather than have to find 51 lawmakers to nominate him, a task that he would struggle to achieve.

“The NEC has agreed that as the incumbent leader Jeremy Corbyn will go forward onto the ballot without requiring nominations from the Parliamentary Labour Party and the European Parliamentary Labour Party,” a party spokesman said in a statement.

The E.U. referendum sparked a wave of resignations from Corbyn’s policy team, with many saying he did not campaign hard enough to prevent the British exit. That response resulted in a no-confidence motion against him passing by a margin of 172 to 40.

But Corbyn retains strong support among the party’s left-leaning rank-and-file members, meaning that he could hold on to power and prolong the standoff with members of Parliament.

The NEC ruling could still trigger a legal challenge from opponents who insist he too should have to garner support from 51 lawmakers, but Corbyn played down such a possibility.

Eagle said she was pleased the NEC had reached a decision.

“I welcome the contest ahead,” she said on Twitter. “And I am determined to win it.”

In defying the pressure to resign, Corbyn has cited the overwhelming mandate he won from the party’s grass-roots members when they elected him leader in September. That has sparked fears that the party could split, as it did in the 1980s, and dilute the center-left’s influence over the Brexit negotiations.

Labour’s internal strife also has fueled tensions among its supporters. Police said Tuesday that Eagle’s constituency office in northern England had been vandalized. Corbyn said he and other lawmakers had received death threats.