LONDON, United Kingdom (AFP) — British Prime Minister Theresa May faces crushing defeat in a historic vote in Parliament on Tuesday over the Brexit deal she has struck with the European Union, leaving the world’s fifth biggest economy in limbo.

With just over two months to go until the scheduled Brexit date of March 29, Britain is still bitterly divided over what should happen next and the only suspense over the vote is the scale of May’s defeat.

The British leader’s last-minute appeals to MPs appear to have fallen on deaf ears and how much she loses by could determine whether she tries again, loses office, delays Brexit — or if Britain even leaves the EU at all.

“When the history books are written, people will look at the decision of this house… and ask: did we deliver on the country’s vote to leave the European Union,” May asked MPs on the eve of the vote, expected after 1900 GMT.

Opposition to the deal forced May to postpone the vote in December in the hope of winning concessions from Brussels.

EU leaders have offered only a series of clarifications but German Foreign Minister Heiko Maas in Strasbourg on Tuesday raised the possibility of further talks while ruling out a full re-negotiation of the text.

“Everything has been done in recent weeks and months to signal our interest in a positive decision,” Maas said.

“However, I am sceptical that the agreement can be fundamentally reopened once again,” he said.

The vote is the climax of over two years of intense national debate after the shock Brexit referendum of 2016 — a result mostly pro-Remain MPs have struggled with.

Hardline Brexiteers and Remainers oppose the agreement for different reasons and many fear it could lock Britain into an unfavourable trading relationship with the EU.

Pro- and anti-Brexit campaigners rallied outside parliament ahead of the vote. One placard read “EU Membership is the Best Deal”, another said: “No Deal? No Problem!”

Uncertainty over Brexit has hit the British economy hard.

The Society of Motor Manufacturers and Traders lobby group warned MPs that Britain crashing out of the EU would be “catastrophic”.

Financial markets will also be watching the result closely, with several currency trading companies roping in extra staff for the vote and at least one putting a cap on trades to avoid excessive currency movements.

“Today’s vote is a foregone conclusion so sterling is unlikely to move significantly,” said Rebecca O’Keeffe, an analyst with online trader Interactive Investor.

“The fireworks will happen after today — when it is clear what happens next,” she said, predicting that a decision not to leave the EU would send sterling shooting up while a no-deal Brexit would send it down to record lows.

Rather than heal the divisions exposed by the Brexit referendum, the vote has reignited them.

Pro-European MPs campaigning to force a second vote say they have faced death threats.

Brexit supporters have also voiced growing frustration with what they see as parliamentary blockage of their democratic vote.

Criticism of the deal is focused on an arrangement to keep open the border with Ireland by aligning Britain with some EU trade rules, if and until London and Brussels sign a new economic partnership which could take several years.

Sammy Wilson, Brexit spokesman with the Democratic Unionist Party (DUP), the Northern Irish party on whom May relies for her Commons majority, told the BBC his party would not be forced into backing the deal by fears over the border.

“We fought (against) a terrorist campaign (in order) to stay part of the United Kingdom,” he said, evoking Northern Ireland’s past conflict.

“We are not going to allow bureaucrats in Brussels to separate us from the rest of the United Kingdom.”

His boss Arlene Foster stressed “we cannot accept the backstop…it does violence to the union.”

Opposition Labour leader Jeremy Corbyn has said May must call an election if she loses on Tuesday and has threatened to hold a confidence vote in her government if she does not.

In the event of a defeat, the government must set out what happens next by Monday at the latest.

Speculation is growing on both sides of the Channel that whatever the outcome May could ask to delay Brexit.

But a diplomatic source told AFP any extension would not be possible beyond June 30, when the new European Parliament will be formed.

The withdrawal agreement includes plans for a post-Brexit transition period to provide continuity until a new relationship is drawn up, in return for continued budget contributions from London.

Without it, and if there is no delay, Britain will sever 46 years of ties with its nearest neighbours with no agreement to ease the blow.