LONDON -- Prime Minister Theresa May was grappling with the biggest crisis of her premiership on Friday after a draft divorce deal with the European Union provoked the resignations of senior ministers and mutiny in her party.

More than two years since the United Kingdom voted to leave the EU in a shock referendum, it is still unclear how, on what terms or even if it will leave the EU as planned on March 29, 2019.

Ever since winning the top job in the turmoil that followed the 2016 referendum, May has sought to negotiate a Brexit deal that ensures that the United Kingdom leaves in the smoothest way possible.

But Brexit minister Dominic Raab resigned over her deal, sending the pound tumbling. Mutinous lawmakers in her own party openly sought to challenge her leadership and bluntly told her that the Brexit deal would not pass parliament.

Asked if she would contest any challenge to her position, May replied: “Am I going to see this through? Yes.” She is due to speak on LBC radio at 0800 GMT.

On Friday, Michael Gove, the most prominent Brexit-supporting minister in her government, gave no comment when asked outside his house whether he would support May. The BBC said May had offered him the job of Brexit minister but he rejected the job.

Sterling, which has see-sawed on Brexit news since the referendum, rose when May struck a deal on Tuesday but has since fallen two and half cents to $1.2788.

Brexit will pitch the world’s fifth largest economy into the unknown. Many fear it will divide the West as it grapples with both the unconventional U.S. presidency of Donald Trump and growing assertiveness from Russia and China.

Amid the deepest political turmoil since the Suez canal crisis, when in 1956 Britain was forced by the United States to withdraw its troops from Egypt, the ultimate outcome remains uncertain.

Scenarios include May’s deal ultimately winning approval; May losing her job; Britain leaving the bloc with no agreement; or even another referendum.

The EU and Britain need an agreement to keep trade flowing between the world’s biggest trading bloc and the United Kingdom, home to the biggest international financial center.

Supporters of Brexit say that while the divorce might bring some short-term instability, in the longer term it will allow the United Kingdom to thrive and also enable deeper EU integration without such a powerful reluctant member.

By seeking to preserve the closest possible ties with the EU, May has upset her party’s many advocates of a clean break, and Northern Ireland’s Democratic Unionist Party (DUP), which props up her minority government.

Meanwhile, proponents of closer relations with the EU in her own party and the Labour opposition say the deal squanders the advantages of membership for little gain.

The deal will need the backing of about 320 of parliament’s 650 lawmakers to pass.

“It is ... mathematically impossible to get this deal through the House of Commons. The stark reality is that it was dead on arrival,” said Conservative Brexit-supporting lawmaker Mark Francois.