Shadow cabinet education secretary Lucy Powell has become the latest senior Labour Party figure to quit the Cabinet as the party launches a full-scale mutiny against its leader, Jeremy Corbyn.

In her letter of resignation, Powell said that the Labour Party faces an “existential threat” following the United Kingdom’s decision to leave the European Union. She expressed her uncertainty with Corbyn’s leadership ability in navigating the tumult. “I do not have the confidence that you [Corbyn] can bring the party together, lead us to a general election, and be an effective opposition.”

Powell, according to Schools Week, was raised in a family of teachers and talked often about her three school-age children while discussing the nation’s educational issues. Powell received plaudits for her work in the shadow cabinet, winning praise for her opposition to Tory policies like forced acadamisation of schools and addressing teacher shortages.

Powell’s decision is part of a stream of resignations meant to force Corbyn to resign that have rolled in after the European Union referendum. In recent days, according to the Manchester Evening News, the shadow cabinet has also lost its health secretary, Heidi Alexander, its transportation secretary, Lillian Greenwood, and its environment secretary, Kerry McCarthy. Additionally, Corbyn fired shadow cabinet’s foreign secretary Hilary Benn after he implored him to step down.

Evidently, Powell and Corbyn have never had a particularly close relationship. She expressed feeling surprised after Corbyn tapped her to serve as the education secretary in his shadow cabinet. Powell claims that she “hardly knew” him at the time of her appointment. The two, like others of Corbyn’s cabinet, as noted by the BBC, developed a neutral, but not hostile, relationship. Indeed, Powell says she has hardly spoken to Corbyn since becoming an MP. Corbyn has received criticism from a number of Labour officials for failing to cultivate constructive relationships with his cabinet secretaries — the kind of relationships necessary to overcome political crises.

Some in the party, however, have refused to disavow Corbyn amidst the calls for restructuring. “I think it’s extraordinary that with the Tory Party in complete and utter disarray that certain factions of the Labour Party have chosen this moment to turn it into a leadership contest,” said Liz McInnes, MP for Heywood and Middleton.

Still, the support of some Labour stalwarts may not be enough to keep Corbyn afloat. Of a dozen local Labour MPs asked about their positions, only one expressed categorical support for Corbyn.

The Labour Party vigorously opposed the Tory-inspired referendum to leave the European Union. Many party officials, including Ann Coffey, who co-authored a letter of no confidence to Corbyn, expressed fury at the “half-hearted” way Corbyn campaigned to remain in the European Union. Indeed, many suspect that Corbyn, who has expressed ambivalence about the European Union before, privately hoped Britain would leave.

Speculation has swirled throughout the United Kingdom, the European Union, and in the United States as to whether Corbyn will resign from his position. The Labour Party is facing as great, if not greater, a political crisis as the British Conservatives, led by David Cameron, who promised in 2015 that the nation would have a referendum on Britain’s EU membership. Cameron has promised to step down as Prime Minister in October. Writhing from the ramifications of an EU-exit, Britain could see new political leaders at the helms of both major political parties.