Prime Minister Theresa May is expected to tell EU leaders today to seize the opportunity to find a real solution to the Irish border.
Mrs May will make her appeal on the eve of a crunch meeting of leaders of the remaining 27 member states today, when they are expected to approve a draft deal on the UK's transition to Brexit, opening the door for talks on trade.
European Council president Donald Tusk raised doubts earlier this week over whether a deal reached by Brexit Secretary David Davis and chief EU negotiator Michel Barnier would be acceptable to all 27. But a senior UK official said last night that "all the indications are positive".
Mrs May will return to the UK after dinner on the first day of the European Council summit today.
London is hopeful that a solution to keep Northern Ireland's border with the Republic open will emerge in the context of a deal allowing trade between the UK and the rest of the EU to be as frictionless as possible.
Mrs May will tell the EU27 leaders: "We have the chance now to create a new dynamic in the talks, to work together to explore workable solutions on Northern Ireland, on our future security co-operation and in order to ensure the future prosperity of all our people. This is an opportunity it is our duty to take and to enter into with energy and ambition."