The botched Brexit deal that Theresa May has put to parliament this week is a monumental and damaging failure for our country. Instead of the sensible agreement the prime minister could have negotiated, it is a worst-of-all-worlds deal that works for nobody, whether they voted leave or remain.

Instead of taking back control, it gives up control. Instead of protecting jobs and living standards, it puts them at risk by failing to put in place the basis for frictionless trade. For two and a half years the Conservatives have been negotiating with themselves, rather than the European Union. The result has been a lockdown withdrawal agreement, which ties Britain either into extending the transition phase at unknown cost – or tips us into a lopsided backstop agreement from which there is no independent exit. As the legal advice the prime minister tried to prevent us from seeing this week spells out, the backstop would “endure indefinitely” without the say-so of the EU.

What that means in practice is that the wish list of the government’s “future partnership” agreement with the EU would remain just that, without the leverage to get a long-term and effective trade deal. Meanwhile, Britain would have no say in either its own customs arrangements or key market regulations. While workers’ rights would be allowed to fall behind, restrictions on state aid to industry would be locked in.

May claims this is just an insurance policy. But it’s now clear the backstop is at the heart of her deal. It would leave Britain with no say in a humiliating halfway house which we couldn’t leave without the EU’s permission. There is no precedent I am aware of for a British government signing up to an international treaty it cannot withdraw from without the agreement of other countries. It is clearly unacceptable.

The only reason the government has agreed such a convoluted package is to manage the warring factions of the Tory party. But it has failed. Instead it has united Conservative leavers and remainers, the DUP and every opposition party against it.

This dreadful deal must be defeated when it is put to the vote next week. We are working with MPs and parties across the House of Commons not only to ensure it is rejected, but also to prevent any possibility of a no-deal outcome.

But its defeat cannot be taken for granted. In an effort to drag Tory MPs back onside, May is claiming that defeat for her deal means no deal or no Brexit, because there is no viable alternative. That is false. Labour’s alternative plan would unlock the negotiations for our future relationship with the EU and allow us to move away from such a damaging backstop.

‘Labour’s alternative plan would ensure an open border in Ireland.’ Photograph: Paul Faith/AFP/Getty Images

A new, comprehensive customs union with the EU, with a British say in future trade deals, would strengthen our manufacturing sector and give us a solid base for industrial renewal under the next Labour government, especially for our held-back communities. It would remove the threat of different parts of the UK being subject to separate regulations. And it would deal with the large majority of problems the backstop is designed to solve.

Second, a new and strong relationship with the single market that gives us frictionless trade, and the freedom to rebuild our economy and expand our public services – while setting migration policies to meet the needs of the economy, not fuelling xenophobia with phoney immigration targets or thresholds – makes far more sense than the prime minister’s dismal deal.

Lastly, we want to see guarantees that existing EU rights at work, environmental standards and consumer protections will become a benchmark to build on – not fall behind and undercut other countries at our people’s expense. These rights and protections, whether on chlorinated chicken or paid holidays, are what people actually want. But the government is determined to trade them away in a race to the bottom.

Labour has very different priorities. Our alternative plan would ensure an open border in Ireland, provide security for investment, give our manufacturing sector a springboard for renewal, ensure we have the powers to rebuild our economy and public services and guarantee world-beating support for workers, consumers and our environment. We are absolutely committed to internationalist cooperation and anti-racist solidarity across Europe, in or out of the EU, and determined to ensure opportunities for students to study in other countries are protected.

Unlike the Norway-plus option now being canvassed among MPs, our plan would not leave Britain as an across-the-board rule-taker of EU regulations without a say. It’s a plan that can be negotiated with the EU, even at this late stage, with most of the building blocks already in place. The EU has shown it is prepared to renegotiate even more complex agreements than this, such as the Lisbon treaty. And ours is a plan I believe could command a majority in parliament and bring the country together.

The stakes could not be higher next week. If the prime minister’s deal is defeated, the government will have lost its majority on the most important issue facing the country and lost its ability to govern. The best outcome in those circumstances would be to let the country decide on the way ahead and the best team to lead it. That means a general election.

In the past, a defeat of such seriousness as May now faces would have meant an automatic election. But if under the current rules we cannot get an election, all options must be on the table. Those should include Labour’s alternative and, as our conference decided in September, the option of campaigning for a public vote to break the deadlock. Two years ago, people voted remain because they wanted an open, international relationship with Europe and a multicultural society. Many voted leave out of anger at the way the political class had left them behind, with crumbling infrastructure and low-paid, insecure jobs. Our job is to unite people with a plan that works for the whole country.

Given the decisions taken in parliament this week, it should now be easier to build support for an alternative plan to bring the country together. The government’s deal must not stand. In those circumstances parliament has shown it is ready to take control, and Labour will give the leadership the country needs.

• Jeremy Corbyn, the MP for Islington North, is the leader of the Labour party