DUP deputy leader Nigel Dodds has insisted Boris Johnson's Brexit proposals will not see Northern Ireland treated differently to the rest of the UK post-Brexit.
Under the PM's plans, there would be an "all-island regulatory zone" on the island of Ireland covering all goods, effectively keeping Northern Ireland in the EU single market.
Crucially, however, the implementation of the regulatory zone would require the consent of the Northern Ireland Assembly, which many have criticised as giving the DUP a veto on any plans.
Speaking on BBC Radio Ulster, Nigel Dodds rejected claims he party had "softened their red lines" by backing a plan that would create a border down Irish Sea, as the Assembly would have to consent to aligning with EU rules first.
"There has to be democratic control and there has to be the consent principle implemented. When the Assembly comes to consider the issue of alignment, then it will be a matter for the Assembly," he said.
"What we have done is set up a process, what we have done is ensure that decision will not be imposed by Dublin, not be imposed by Brussels, not be imposed by anyone without the agreement of politicians in Northern Ireland.
"Only if unionists in the Assembly agree to it - that's the process point. We would only agree to anything if it's in the economic best interest of Northern Ireland and it didn't create any trade barriers, or borders, between the rest of the United Kingdom and Northern Ireland."
Boris Johnsons's proposals would also see Northern Ireland leaving the EU customs union, meaning there would have to be checks on goods moving from Northern Ireland to the Republic.
The plan insisted, however, checks would not take place "at, or even near" the border and only a "very small proportion" of good would have to undergo physical checks at either traders' premises or other designated locations on the island of Ireland.
Brexit Secretary Stephen Barclay told ITV's Good Morning Britain: "Well actually, today there's a border, there's a border in terms of currency and there's a border in terms of tax, but in terms of putting no infrastructure at the border, in terms of ensuring that we are consistent with the Belfast Good Friday Agreement, then it does do that, that's exactly what these proposals do."
Explaining how goods will be checked, he said: "The proposals, in terms of having a regulatory zone, clearly reduce significantly the need for checks.
"In terms of then on customs, coming out of a customs union inevitably requires there to be some customs checks.
"And those will be done at premises, and we've set out in the paper all the detail as to how that would work."
On the issue of Northern Ireland not having a functioning executive, Mr Barclay told Good Morning Britain: "I think that is one of the key priorities, and part of this is about giving democratic control back to the people in Northern Ireland.
"And one of the concerns with the backstop was that it would have involved laws applying over which people wouldn't have a vote, and it was at odds with the Belfast Good Friday Agreement in terms of having the consent of both sides of the community, both communities in Northern Ireland."
He again reiterated that one of the "key issues" is to get the Northern Ireland Executive up and running.
"Whilst this issue is still live it's actually an impediment to getting the Executive in place," he said.
"So let's get a deal, let's leave in a way that is consistent with the Belfast Good Friday Agreement, avoid the disruption that many in Northern Ireland want to see avoided in terms of no deal, because many of these checks will be required to protect the integrity of the single market in the event of no deal, and then let's get the Executive up and running because that's what people want to see."