Theresa May’s EU debacle has forced Labour to pull the trigger on its final Brexit option: calling for a second referendum. Get ready for the chaos.

A “Vote LEAVE” campaign bus parked outside the Houses of Parliament in July 2016. Jack Taylor / Getty.

peaking from a summit meeting in Egypt this week, Theresa May told reporters that parliament would hold another vote on whether to accept her Brexit deal by March 12, seventeen days before the United Kingdom is scheduled to leave the European Union. The announcement infuriated an already deeply divided country and parliament: with little clarity, May has been acting like a friend in charge of booking a holiday who refuses to let anyone else know the details, divulging only the most meager information under extreme duress, with no one able to plan or even guess the likely schedules.

It is entirely possible she simply has no concept of linear time progression, rather than just being a terrible politician: on the plane to the summit she complained to a reporter who’d asked what she planned to do if she lost the next vote, “Why is it that people are always trying to look for the next thing after the next thing after the next thing?” Simply put, she is playing chicken: trying to terrify politicians, through a lack of detail, into voting through her withdrawal agreement by running down the clock.

Labour has repeatedly demanded she take the no-deal option, in which the UK crashes out of the EU, off the table, since it would likely cause widespread panic, disruption to food and medicine supplies, and massively complicate all borders but especially the border between the Republic of Ireland and the north of Ireland. Yesterday, with few other options available, Jeremy Corbyn announced Labour would table an amendment for a second referendum.

Unlike the Conservatives, Labour’s policies are in part established by voting delegates at the party conference: last September, delegates backed a motion stating that Labour should campaign first and foremost for a general election. If that was not forthcoming, and if parliament rejected the Brexit deal the prime minister put forward, the party should campaign for a public vote. Speaking to Channel 4 news, shadow foreign secretary Emily Thornberry told the presenter that Labour would back a ballot offering a choice between remaining in the EU or accepting May’s deal. Labour was not explicitly calling for the referendum to be overturned, but was keeping options on the table to allow the public a greater say if May’s proposed Brexit deal was likely to harm the country. The complete mayhem and parliamentary deadlock over May’s disastrous deal has now pushed forward Labour’s move towards demanding a second vote, with the party working through the strategy laid out in the conference motion.

What happens now? The party will put forward an amendment calling for a second referendum and Labour will likely whip its MPs to vote for it. May will whip her politicians to vote against a public vote on her deal. Many Conservative MPs have vocally and publicly attacked May’s deal, and she has failed to drag the withdrawal agreement through the House of Commons, facing a series of humiliating defeats. Those rebels will now be forced to prove precisely how rebellious they genuinely are. It’s entirely likely the amendment will fall, due to the parliamentary arithmetic.

But if enough Tories do come out for a second vote, the outcome of a second referendum is entirely unpredictable. The original vote came out only slimly for leaving the EU. The country remains deeply divided, and polling suggests few voters have changed their minds. Labour will commit to campaigning for Remain, while the Conservatives will back May’s deal.

The result will hinge on three factors: turnout, demographics and messaging. Turnout could swing either way: ardent leavers are likely to come out again, ditto remainers. But as with all campaigns, the most vociferous make up the minority of voters. Those staying home due to Brexit fatigue or indifference could cause the result to swing either way. In terms of demographics, older voters tended towards Leave, younger generations were more likely to vote to remain in the EU. Many who were too young to vote in 2016 will now be eligible three years later, but they’re also the demographic least likely to turn out: Leave campaigners will be hoping young people stay away from the ballot box, while Remain campaigners will need to register young voters and beg them to turn out to vote on the day.

Messaging is the greatest difficulty: in the original referendum the various Leave campaigns played fast and loose with facts and arguments; the infamous red bus that promised leaving the EU would hand the National Health Service an extra £350 million a week became a flashpoint of the campaign, and was criticized by the UK Statistics Authority for willful distortion of the facts. In October, polling found that almost half the public still believed the figure. Lying for political gain is nothing new, but referenda allow false claims to spread like wildfire and are rarely corrected until after the vote has passed. The Remain campaign struggled to find a message about the benefits of EU membership that could connect with many voters, and the Irish border question was barely mentioned in the campaign. Leave can simply rerun its arguments from the first campaign, but for Remain campaigners to stand a chance of winning they will need to argue forcefully that the threat to peace in Ireland and the fallout for food and medicine supplies make leaving the EU not worth it.

But this may all be moot: whether an amendment to force a second vote can get through parliament at all remains to be seen. Whatever the outcome, Britain still stands on the precipice of a chaotic unknown, and the intense political divisions that have riven the UK in the three years since the referendum have only deepened.