DUP leader Jeffrey Donaldson has again said his party will not re-enter power-sharing at Stormont unless the Northern Ireland Protocol is overridden or fundamentally changed.
In his speech to his party conference in Belfast, he said the removal of customs checks on goods coming into Northern Ireland from Britain would not be sufficient.
The Lagan Valley MP said Northern Ireland cannot be subject to different laws than other parts of the UK.
Mr Donaldson reiterated his party's support for the Northern Ireland Protocol Bill, which if enacted would override much of it.
"Let me be clear," he told delegates.
"Either the Prime Minister delivers the provisions of the Protocol Bill by legislation or by negotiation and ensures that our place in the United Kingdom is restored … or there will be no basis to re-enter Stormont.
"On this issue it is not words but actions we need to see and we will judge any outcome on the basis of actions not words.
"Some lay great emphasis on cutting the number of checks on goods entering Northern Ireland from Britain.
"If that were to happen they say all our problems would be sorted notwithstanding that the Protocol has not yet been fully implemented.
"The truth of course is that the checks on the Irish Sea border are the symptom of the underlying problem namely that Northern Ireland is subject to a different set of laws imposed upon us by a foreign entity without any say or vote by any elected representative of the people of Northern Ireland.
"As Britain has secured its freedom to de-regulate or move in a different direction of travel on aid or taxation Northern Ireland is going to constantly face new barriers because we are tied to a different set of laws.
"That is simply not sustainable and is incompatible with devolution, which requires the support of unionists as well as nationalists if it is to function.
"For the benefit of those watching in London and Brussels, let me restate our clear commitment."
In a message directed at the British Government and the EU, the DUP leader said his party will go back into power sharing if "decisive action is taken on the Protocol that restores our place fully within the United Kingdom."
He also said his party does not fear a fresh Assembly election, which British prime minister Liz Truss and Northern Secretary Chris Heaton-Harris have said will be triggered if power sharing is not restored by 28 October.
"We do not fear the prospect of a fresh election, far from it," he said.
"If in the absence of this government righting the wrongs visited upon Northern Ireland the Secretary of State calls an Assembly election... we are ready and we will take our case to the people as the lead party of unionism.
"We will campaign as never before to secure a further fresh mandate from the people.
"The Government needs to tread sensitively and act wisely if they wish to see unionist confidence rebuilt and the conditions created for durable power sharing."
Mr Donaldson said he still believes in the principle of devolution but added that it "can only work with the support and buy in of unionists and nationalists."
"The imposition of the Protocol upon Northern Ireland has damaged and undermined the workings of our institutions," he said.
"They cannot work without the restoration of the delicate political balance negotiated over many years and which has been disrupted by the Protocol."
Mr Donaldson also expressed his sympathies to the families of those killed and injured in Creeslough.
At the start of his speech, he said he wanted to "express our sympathies to those families who have been bereaved in the tragic events in Donegal yesterday afternoon.
"Those injured as a result of this explosion are foremost in our thoughts. We want to extend our thanks to all the emergency services for their efforts to save life from both sides of the border."
He added: "This is what being a good neighbour is all about I want to assure the people of Cresslough of our collective prayers and want them to know that they will continue to be in our thoughts in the days ahead."
