Labour will launch the first step in an audacious cross-party attempt to block a new prime minister from forcing through a no-deal Brexit in October.

The shadow Brexit secretary, Keir Starmer, threw down the gauntlet to Tory cabinet ministers including Amber Rudd and Philip Hammond, saying they should back Labour’s attempts if they were serious about preventing no deal.

If passed, the motion would give MPs control of the parliamentary agenda on 25 June. The same motion could then potentially be used to begin legislation to prevent the UK from leaving the EU without a deal.

The motion, which Labour will table during the opposition day debate on Wednesday, has the backing of the former Conservative minister Oliver Letwin and the leaders of the Scottish National party, Plaid Cymru, the Liberal Democrats and the Greens.

Unlike typical opposition day debates, the motion, if passed, will be binding, but it will need to secure the support of more Conservative MPs.

The plan, which has been a closely guarded secret, comes as several Tory leadership contenders, including Boris Johnson – who will launch his campaign on Wednesday – emphasised their willingness to accept a no-deal Brexit.

Q&A What does a no-deal or WTO-rules Brexit mean? Show If the UK leaves the EU without a deal it would by default, become a “third country”, with no overarching post-Brexit plan in place and no transition period. The UK would no longer be paying into the EU budget, nor would it hand over the £39bn divorce payment. The UK would drop out of countless arrangements, pacts and treaties, covering everything from tariffs to the movement of people, foodstuffs, other goods and data, to numerous specific deals on things such as aviation, and policing and security. Without an overall withdrawal agreement each element would need to be agreed. In the immediate aftermath, without a deal the UK would trade with the EU on the default terms of the World Trade Organization (WTO), including tariffs on agricultural goods. The UK government has already indicated that it will set low or no tariffs on goods coming into the country. This would lower the price of imports – making it harder for British manufacturers to compete with foreign goods. If the UK sets the tariffs to zero on goods coming in from the EU, under WTO “most favoured nation” rules it must also offer the same zero tariffs to other countries.

WTO rules only cover goods – they do not apply to financial services, a significant part of the UK’s economy. Trading under WTO rules will also require border checks, which could cause delays at ports, and a severe challenge to the peace process in Ireland without alternative arrangements in place to avoid a hard border.

Some no-deal supporters have claimed that the UK can use article XXIV of the General Agreement on Tariffs and Trade (Gatt) to force the EU to accept a period of up to 10 years where there are no tariffs while a free trade agreement is negotiated. However, the UK cannot invoke article XXIV unilaterally – the EU would have to agree to it. In previous cases where the article has been used, the two sides had a deal in place, and it has never been used to replicate something of the scale and complexity of the EU and the UK’s trading relationship. The director general of the WTO, Roberto Azevêdo, has told Prospect magazine that “in simple factual terms in this scenario, you could expect to see the application of tariffs between the UK and EU where currently there are none”. Until some agreements are in place, a no-deal scenario will place extra overheads on UK businesses – eg the current government advice is that all drivers, including lorries and commercial vehicles, will require extra documentation to be able to drive in Europeif there is no deal. Those arguing for a “managed” no deal envisage that a range of smaller, sector-by-sector, bilateral agreements could be quickly put into place as mutual self-interest between the UK and EU to avoid introducing or to rapidly remove this kind of bureaucracy. Martin Belam

Those who have worked on the plan include leading former and current Conservatives including Nick Boles and Dominic Grieve.

A similar move in April by Letwin and the Labour MP Yvette Cooper passed by one vote after 14 Tory MPs rebelled. Conservative sources who have worked behind the scenes on the proposal believe it may be difficult to convince some party colleagues to back a plan based on a Labour opposition day motion, even if they broadly support its objective.

“We have to persuade them that it is currently the only hook available,” one Tory source said.

Jonathan Djanogly, one of the Tories who backed Theresa May’s deal but also supported previous efforts by Letwin to stop no deal, said he would support the motion.



“As far as I know the last time that prorogation was used to stymie political debate was just before the civil war. If we have a chance to stop it tomorrow that chance should be taken,” he told the Guardian.

Johnson, as well as Andrea Leadsom, Dominic Raab and Esther McVey, have vowed that if they win the Tory leadership, they will take the UK out of the EU on 31 October, regardless of whether or not a deal is in place.

Raab has also refused to rule out the option of proroguing parliament in order to force through a no-deal Brexit, something other candidates have said they would not countenance.

Starmer said the debate over a no-deal Brexit in the Tory leadership contest had “descended into the disturbing, the ludicrous and the reckless”, and had forced MPs to act.

“MPs cannot be bystanders while the next Tory prime minister tries to crash the UK out of the European Union without a deal and without the consent of the British people,” he said.

“That’s why we are taking this latest measure to end the uncertainty and protect communities across the country. My challenge to MPs who disagree either with a no-deal Brexit or proroguing parliament is to back this motion and act in the national interest.”

The motion has been signed by Corbyn and the Labour chief whip, Nick Brown, as well as Letwin, the SNP’s Ian Blackford, the Lib Dems’ Vince Cable, Plaid Cymru’s Liz Saville Roberts and the Green MP, Caroline Lucas.

It is unclear what form those measures to prevent a no-deal departure, which remains the legal default, could take.

Some MPs, including the Lib Dem leadership candidate Ed Davey, have suggested making it the legal default that a prime minister must revoke article 50, rather than leave without an agreement. It is unlikely, however, that such a radical move could garner the necessary cross-party backing.

Letwin, who has backed Michael Gove in the Tory leadership contest, is likely to face criticism from party colleagues for supporting the move. A Gove campaign source said: “All leadership candidates will need to win support of colleagues across the party. Michael has always been clear that no deal must remain on the table.”

Steve Baker, the deputy chair of the hard-Brexit European Research Group, said Tories including Letwin were risking the chance of a general election that could result in the Conservatives being wiped out by the Brexit party.

Baker, who has backed Johnson, said: “Oliver Letwin brings closer a general election which could leave Conservatives holding as few as 26 seats. Colluding with this Labour leadership to deny government control of the Commons business is unconscionable for being firmly against the national interest.”

Corbyn had hinted his party would restart efforts in earnest to prevent a no-deal Brexit in a speech to Labour MPs on Monday night, a meeting that descended into bitter criticism of the party’s Brexit strategy.

He said the party would “never accept no deal … nor will MPs from across parliament. We will work on a cross-party basis to block a no-deal outcome.”

MPs criticised Labour’s equivocation on another referendum ahead of the European elections last month, which many blamed for the party’s poor performance.

Several MPs who spoke out in the tense meeting had not publicly criticised the Labour leader previously, including Marie Rimmer, who told the meeting she had found it difficult to vote Labour, and Lloyd Russell-Moyle, who argued for a members’ ballot on a change of policy and said senior staff determining Labour’s strategy should not be exempt from criticism.

The Labour MP Anna Turley said the meeting was “messy and difficult”. “The cleaners are probably still mopping up the blood on the carpet,” she said.

Turley, who backs a second referendum, told the BBC: “Our results have not been going how we want and we have to be honest about that. It’s no good pretending everything’s fine while the Tories implode. W we are not in the position that we should be and we’ve got to do better.”