The British Foreign Secretary has expressed determination to secure a deal on the Northern Ireland Protocol that can command universal support in Northern Ireland.
Liz Truss made the comments after a day of meetings with business and political leaders in Belfast.
The visit came amid continued warnings from the DUP that it will walk away from the devolved institutions at Stormont if major changes to the Irish Sea border trading arrangements are not secured rapidly.
After meeting with Ms Truss at Stormont House, the DUP identified 21 February as a fresh deadline for when the British government needs to deliver progress in its negotiations with the European Union.
First Minister Paul Givan warned that the British government must take unilateral action and suspend the operation of the protocol's trading arrangements if an agreed position cannot be reached with the EU.
But Sinn Féin has warned that any attempt to suspend the protocol by triggering its Article 16 mechanism would cause more uncertainty in Northern Ireland.
Ms Truss said: "What I want is a deal that works for everyone. We are making progress. We're having constructive talks.
"I want to make significant progress by February. That's important but it's important that we secure the support of all of the communities in Northern Ireland, including the unionist community."
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'I care passionately about the Union' - Truss
A DUP walkout from Stormont could result in the institutions collapsing.
Asked if the British government had a plan B in those circumstances, or if she cared if devolution collapsed, Ms Truss said. "I care passionately about the Union.
"I care passionately about making sure that we deliver for the people of Northern Ireland. That's why I'm here today, to listen to people, to make sure that's reflected in the negotiations we have with the European Union.
"I completely understand the frustration people feel and the need for rapid progress, and that is why we are in intense negotiations with the EU to sort out the very real issues here.
"People need to be able to get access to the same goods here in Northern Ireland that they can in GB.
"We can't have a situation continuing where communities are struggling to get those goods, where there is different treatment here from what there is in Great Britain, so we need to sort those issues out, and I'm very exercised by that."
Ms Truss, who is leading UK negotiations with the EU over the protocol, accompanied Northern Ireland Secretary Brandon Lewis during a meeting with Mr Givan and Sinn Féin Deputy First Minister Michelle O'Neill at Stormont.
Speaking afterwards, Mr Givan said progress in negotiations needs to be made "imminently".
He said: "Liz Truss has indicated that she is making progress with the European Union and obviously 21 February is a very significant date in terms of what progress will have been made or not made."
A meeting of the Joint Working Committee on the Withdrawal Agreement takes place on that date.
He added: "I pressed the Foreign Secretary about the need to take action in the absence of there being progress and an agreed outcome with the European Union.
"The Foreign Secretary indicated that the UK government does stand ready to take action, she mentioned the use of Article 16, but she prefers to get an agreed position with the European Union."
He added: "I have emphasised the absolute critical nature of that progress being made because the protocol is causing instability to these institutions. It is damaging our economy and this is having a real impact on Northern Ireland.
"So we need to see that progress, we need to see that imminently, and we also need to see action taken by the UK government if there isn't an agreed outcome."
The meeting came a day after DUP leader Jeffrey Donaldson warned he could not guarantee Mr Givan would still be in position next week.
Mr Givan said: "I hope that I am still in this position next week because there are huge issues that we need to deal with as an Executive.
"That is why it is critical the UK Government take action, why it is critical they get an agreed position with the European Union, and if they don't get that then let the UK government take action because the people of Northern Ireland need us to be here delivering."
Ms O'Neill said: "Liz Truss repeated her words that there is a deal to be done, that she is working to find solutions.
"But that is yet to be seen in terms of striking an agreed way forward.
"I encouraged her to listen very carefully to the views of those in the community and voluntary sector that she will meet with.
"She needs to hear loud and clear that the DUP do not speak for the majority here.
"She needs to hear loud and clear that triggering Article 16 serves no purpose other than to cause more uncertainty, and she needs to hear the reality on the ground that the majority here want the protocol to work and they want solutions to be found."
'Time is important'
Meanwhile, the Minister for Foreign Affairs told the Dáil that "a key window" exists over the next month to secure a deal on the Northern Ireland Protocol.
"I think time is important here," Simon Coveney said.
"Between now and the end of February there is a key window to try to find accommodation and agreement."
Since the appointment of Ms Truss, Minister Coveney said that contacts have become "a lot more personal and a lot warmer".
However, the two sides are still far apart, and "she certainly hasn't softened the UK government's position on the key issues," he said.
Yesterday, UK Prime Minister Boris Johnson accused Brussels of implementing the Northern Ireland Protocol in an "insane" and petty way.
Mr Johnson told MPs he never thought when negotiating the agreement that scores of businesses would stop supplying Northern Ireland.
He adopted a noticeably more abrasive tone than Ms Truss, who told MPs earlier this week "there is a deal to be done" to resolve the deadlock over the post-Brexit trading arrangements.
The protocol is aimed at avoiding a hard border with Ireland but has created a series of economic barriers on Irish Sea trade.
Additional reporting PA
