British prime minister Theresa May has delayed a parliamentary vote on Brexit on the day the European Court of Justice ruled the country can unilaterally cancel its withdrawal from the EU.

Opposition from both sides

May is struggling to win a majority for her Brexit deal, which would see the United Kingdom leave in March 2019 but continue to obey EU rules through the end of 2020 in order to ease the transition.

The right of her Conservative Party and its allies in Northern Ireland object to the so-called backstop in the withdrawal agreement, which could keep the United Kingdom in a customs union with the EU indefinitely.

The backstop is designed to keep the border between Northern Ireland and the Republic of Ireland open, something that has helped keep the peace between Catholics and Protestants in Ulster for twenty years. To avoid the need for border controls, Northern Ireland would have to remain in a customs union with the EU. To avoid the need for border controls between Northern Ireland and the island of Great Britain, the whole the UK would have to remain in such a customs union. Brexiteers consider this a betrayal of the 2016 referendum.

The opposition Labour Party, the Liberal Democrats and the Scottish National Party, on the other hand, argue that the withdrawal agreement puts too much distance between the UK and its biggest trading partners. They favor a Norway-style arrangement, under which Britain would remain in the European single market. But that would require accepting free movement of EU nationals, which May has ruled out.

Vote

The expectation is that seventy to eighty members of May’s own coalition will vote against the deal, which means she needs about the same number of lawmakers from other parties to switch sides.

A vote had been scheduled for Tuesday. May told the House of Commons this afternoon she is postponing it.

No Brexit?

The European Court of Justice has given Britain a possible way out.

In a case brought by Scottish politicians, the Luxembourg-based court ruled that the country can unilaterally rescind its Article 50 notification of withdrawal and remain in the EU on the terms it enjoys now — with exemptions from the euro and the Schengen free-travel area.

EU and UK lawyers had argued that Article 50 notification should be binding. The bloc’s fear is that recalcitrant member states might now use the procedure as a bargaining chip. The British government argued the case was purely hypothetical as “the UK does not intend to revoke its notification.”