If negotiations she is leading fail, the foreign secretary, Liz Truss, has warned that she is prepared to unilaterally override parts of the post-Brexit agreement on Northern Ireland.
In her first face-to-face talks this week, Truss said she would suggest constructive proposals to her EU counterpart, Maro ef ovi.
She said she was willing to trigger article 16 of the Northern Ireland protocol, which would suspend parts of the treaty designed to prevent a hard border with the Republic, if a deal can't be struck.
After Lord Frost resigned as minister of state for the EU last month, the foreign secretary was handed over responsibility for the negotiations.
Truss is hosting a vice-president of the European Commission, ef ovi, at the Chevening country retreat afforded to the foreign secretary when he visits on Thursday.
In the Sunday Telegraph, she said it was her absolute priority to deal with the unintended consequences of the protocol to maintain peace in Northern Ireland.
When Maro ef ovi comes to us for our first face-to-face talks this week, I will be putting forward our constructive proposals to solve the situation. She argued that the current issues are myriad and manifest, citing issues such as bureaucracy on sending parcels between Northern Ireland and Britain and problems procuring kosher food.
Truss said he was prepared to work night and day to negotiate a solution.
I will not sign up to anything that makes the people of Northern Ireland unable to benefit from the same decisions on taxation and spending as the rest of the UK or sees goods moving within our own country being subject to checks.
My priority is to protect peace and stability in Northern Ireland. I want a negotiated solution, but if we have to use legitimate provisions, including article 16, I am willing to do that. ef ovi warned last week that if Truss took the drastic step, the foundation of the entire deal between the UK and the EU would be jeopardised.
This is a very distracting element in the discussions. He told the German newspaper Der Spiegel that you try to achieve something together and bam there is the threat of article 16 again.
It touches on the fundamentals of our relationship. The protocol for Northern Ireland was the most complicated part of the negotiations, and it is the foundation of the whole deal. Without the protocol, the whole system will collapse.