MPs have voted to reject changes to the government's Northern Ireland Protocol Bill in the House of Commons.
If it passes, the legislation would effectively tear up parts of the post-Brexit trading arrangements.
The SDLP, Alliance and Labour tried to water the bill down with various amendments during Wednesday's debate but none were successful.
MPs voted 308 to 230, majority 78, to reject the SDLP amendment.
It comes after the DUP said that, if the bill does become law, it will provide the basis for restoring the Executive.
Party leader Sir Jeffrey Donaldson told the House of Commons if that were to happen he would return to Stormont as Deputy First Minister.
He added: "I'm absolutely convinced of that and my party has stated clearly that if this Bill becomes law, we believe that provides the basis for restoring the political institutions in Northern Ireland, including the executive, and I've already committed to leave this place and to return to Stormont as the deputy first minister as part of that executive.
"Therefore I have a personal commitment to the restoration of the political institutions, as does my party."
Meanwhile, the Secretary of State has insisted the government is giving "100% attention" to the protocol legislation despite the Tory leadership race.
Shailesh Vara said the Bill was not being forgotten about.
"It is receiving 100% attention," he said.
He added: "Yes, the Conservative Party is in the process of electing a new leader but that is not to say that legislation is not continuing, as it rightly does both for Northern Ireland and the rest of the United Kingdom."
Mr Vara replaced Brandon Lewis as Secretary of State last week and says politicians are keen to find a solution.
He said: "I think most political parties and many of the business community and individuals in Northern Ireland recognise that the system that we have at the moment is not working correctly and they all recognise that there ought to be some change.
"And what we are prepared to do and very happy to do, and indeed have been trying to do, is to engage and the UK Government has been engaging with the EU to try and take a common sense approach and move forward.
"Sadly, however, whilst people are saying they want to engage in dialogue and conversation and this should be a negotiated settlement, sadly when you sit at the table, the response is sometimes 'well, sorry, but you know, you've signed up to this, so we're going to have to get on with it'.
"So, if that attitude prevails, then I'm afraid the people of Northern Ireland will not get the common sense approach that I want."
"So, what I want to do is for everyone to recognise that what is there at the moment is not working, and we need to talk and make it work and this (the Bill) is a last resort, but you know we are determined that if it's necessary we will pass that legislation, because it's in the interest of the nearly 1.9 million people in Northern Ireland," he added.
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