The DUP leader Jeffrey Donaldson is to make a speech in Belfast on Thursday morning setting out the next steps in his party's campaign to "remove" the Northern Ireland protocol.
A Stormont source said Mr Donaldson was expected to warn that talk must now be matched with action or there would be "consequences".
Speaking ahead of his address, Mr Donaldson said that while he welcomed the UK government’s extension of grace periods earlier this week in the “absence of actual progress, we cannot remain in this political limbo”.
The protocol, he said, was "not just a threat to the economic and constitutional integrity of the United Kingdom, it is having real world impacts on our economy" and was "not simply a unionist issue."
It was “essential”, he said, that three key issues - around the movement of goods, standards and governance - were addressed.
The solution, Mr Donaldson said, was “not simply a question of limiting checks at the border or moving the checks from the Border”.
“It must mean that, save for the most limited circumstances, EU law would not apply in Northern Ireland.
“And it must mean that where there is a dispute, we are not being asked to argue our case in front of a judicial system created by one of the parties to that dispute.”
Unionist parties, including the DUP are opposed to the Northern Ireland protocol because it places a border in the Irish Sea between Northern Ireland and the rest of the UK.
Political consequences
In Thursday’s speech Mr Donaldson is expected to set out in more detail the political consequences if the dispute over the protocol is not resolved.
These could include potential implications for devolution, North-South relations and relations within the Northern Executive.
Earlier this year, under the leadership of Arlene Foster, the DUP announced it would stop all cross-border activity related to the protocol as part of a five-part plan to have Northern Ireland "freed from the protocol."
Following his maiden speech as DUP leader in July, Mr Donaldson told reporters that Dublin “could not on the one hand demand and expect normality in the relationship between Northern Ireland and the Republic and at the same time support something that damages our relationship with the United Kingdom”.
However he has previously stopped short of threatening to collapse the Stormont power-sharing institutions.
Asked two weeks ago if he would walk away from the institutions if the situation over the protocol was not resolved, he said “I don’t want to be in a situation where political institutions collapse, but I don’t want to be in a situation where we sustain a situation where our relationship with the rest of the UK is harmed on a daily basis”.
Mr Donaldson's speech comes as the European Commission vice president, Maros Sefcovic, begins a two-day visit to Northern Ireland.
He will meet business and civic leaders and politicians in the North on Thursday, and is due to deliver a speech at Queen's University, Belfast on UK/EU relations and to meet the North South Ministerial Council on Friday.
Speaking ahead of his meeting with Mr Sefcovic, the SDLP leader Colum Eastwood said political leaders in the North needed to "set aside their ideological differences and prejudices" around the protocol and "act in the best interests of people here" by "embracing the opportunities".
