The DUP has endorsed Boris Johnson’s offer to the European Union.
It includes the creation of an all island regulatory zone for agriculture, food and all manufactured goods.
The party said the latest proposal ensures consent of the representatives of the people of Northern Ireland to aligning with EU trade rules, before regulations come into force.
But Sinn Féin described the prime minister’s plan as “an act of political sabotage”.
The UK proposal is that a revived Stormont Assembly and Executive would have to give their consent for the trade arrangements to enter into force before the end of a transition period, which is due to last until 2021 and then renew that approval every four years.
Under Assembly cross-community voting rules this would give both unionists and nationalists a veto over aligning with the EU.
If the Assembly withheld its consent, Northern Ireland would revert to the trade regulations which apply elsewhere in the UK.
If the arrangements are approved by the Assembly and Executive, Northern Ireland would adopt EU trade regulations. However, under the UK proposal it would remain within the UK customs territory meaning there will be a requirement for some customs checks on goods moving across the border.
The European Commission said it will “examine [the proposals] objectively”.
A DUP statement said that it was important “to secure a balanced and sensible deal as we leave the European Union”.
It continued: “Those who know anything about Northern Ireland will appreciate that these issues will only work with the support of the unionist as well as the nationalist community.
“The DUP has always indicated that the United Kingdom must leave the EU as one nation and in so doing that no barriers to trade are erected within the UK.
“This offer provides a basis for the EU to continue in a serious and sustained engagement with the UK Government without risk to the internal market of the United Kingdom.”
The DUP said that changes would be required to the draft withdrawal treaty and “we welcome the fact that all sides now recognise that requirement in order to secure agreement”.
“These proposals would ensure that Northern Ireland would be out of the EU Customs Union and the Single Market as with the rest of the United Kingdom.”
‘Protect the union’
But Sinn Féin deputy leader Michelle O’Neill said that the EU must not accept the proposals as they “failed to meet the objectives of the Irish backstop”.
She said: “While a no-deal Brexit was avoided in March and April, there is no optimism that this will be the case come 31 October.
“This is catastrophic for citizens and for business.”
In his speech to the Conservative Party conference on Wednesday, Mr Johnson described his plan as a “compromise for both sides” which would “protect the union”.
His offer is for an “all-island regulatory zone”, which would mean Northern Ireland would have to follow EU rules for goods.
There would be additional checks on goods moving from Great Britain to Northern Ireland, but the UK would not apply further checks on goods entering Northern Ireland from Ireland.
Checks relating to the single market are about product standards, to ensure goods comply with EU regulations.
However, Northern Ireland would leave the EU customs union with the rest of the UK, so there would have to be new customs checks between North and South.
Those checks would look at customs documents and the payment of tariffs, which allow goods to cross the border in the first place.
The government proposals suggest the vast majority of checks could be carried out electronically – but thinks a small number of physical checks would have to take place, either at business premises or at points on the supply chain.
When unconfirmed reports of the UK’s proposals emerged late on Tuesday night, Tánaiste (Irish deputy prime minister) Simon Coveney said he had not seen the details but he, again, rejected the idea of a time limit.
Mr Coveney told Virgin Media’s The Tonight Show on Tuesday: “Our position has been very clear on a time-limited backstop. If it’s time-limited, and you can’t answer the question what happens at the end of that time period, then it’s not a backstop at all.”
He added that if the reports were true, then “it doesn’t look like it’s the basis for an agreement, that’s for sure”.
The leader of Northern Ireland’s Social Democratic and Labour Party (SDLP) Colum Eastwood said the proposals were “dead on arrival”.
He has called on the leaders of the UK’s biggest parties to vote Mr Johnson out of office.
Alliance leader and MEP Naomi Long said: “This proposal is in many ways the worst of both worlds, as we’ve gone from having no new borders to having two.”
Ulster Unionist leader Robin Swann claimed the PM’s proposals would see Northern Ireland left in a “perpetual cycle of uncertainty”.
He said: “The prime minister and the DUP are fooling no-one with these proposals. This new protocol should be deeply concerning for all those who have the long term economic and constitutional welfare of Northern Ireland and its people at heart.
“Northern Ireland would become a hybrid part of the UK with a border up the Irish Sea.”