DUBLIN • The key to British hopes of moving on to trade talks with the European Union after it quits the bloc lies in Dublin, said the European Council president as Ireland called for "credible" solutions from London for the Irish border.
Avoiding a return to a "hard border" on Ireland is the last major hurdle before Brexit talks can advance to trade ties and a possible two-year Brexit transition deal.
But European Council president Donald Tusk said that while the EU negotiating team represents the interests of the 27 other members, Ireland will have the final say on the border issue.
"Let me say very clearly: If the UK offer is unacceptable for Ireland, it will also be unacceptable for the EU," Mr Tusk said in Dublin at a joint press conference with Irish Prime Minister Leo Varadkar last Friday.
"The key to the UK's future lies, in some ways, in Dublin, at least as long as Brexit negotiations continue."
Mr Tusk confirmed he had given British Prime Minister Theresa May a deadline of tomorrow to make a final offer on Irish border conditions before EU heads of government decide whether there is "sufficient progress" on a UK-EU divorce settlement to merit opening talks on the future relationship.
If London meets the three key conditions set by the EU - on its financial bill for leaving, the rights of expatriate citizens and the border - then leaders could give the green light to trade talks at the summit on Dec 14 and 15.
With significant headway on the financial settlement and citizen rights now apparently in the bag, a deal on the Irish border appears to be the final hurdle.
The political and economic stakes are high. The economy of Ireland, north and south, has become deeply integrated since the EU single market's creation in 1993, and only road signs now mark the frontier. Free-flowing commerce, together with the 1998 peace deal between Northern Ireland's Protestants and Catholics, has transformed previously neglected areas on both sides of the boundary.
Mr Varadkar said that while progress on the border issue has been made, the next few days would be crucial and that Ireland would not be afraid to use its veto if necessary.
Dublin wants Mrs May to spell out in writing how she intends to make good on a commitment to avoid turning the clock back to a border of Customs and security checks. It says the best way to do so is to keep regulations the same on both sides of a border that will be Britain's only land boundary with the EU after Brexit.
Mrs May's government has said Britain will leave the EU's single market and Customs union but wants the Irish border to remain open, a stance that EU officials say is contradictory.