European Union leaders have offered a united chorus of "No" to Britain's belated bid to negotiate changes to the Brexit divorce deal.
Speaking with British Prime Minister Theresa May over the phone, Irish Prime Minister Leo Varadkar - whose economy stands to suffer most from a 'no-deal' Brexit - told Mrs May he would not accept her plans to renegotiate a post-Brexit arrangement for the Irish border.
"The Taoiseach [PM] set out once again the unchanged Irish and EU position on the Withdrawal Agreement and the backstop, noting that the latest developments had reinforced the need for a backstop which is legally robust and workable in practice," a spokesman for then Irish Government said after the two leaders spoke by phone.
Buoyed by winning a vote in Parliament, Mrs May has vowed to secure "legally binding changes" to the Withdrawal Agreement and is set for further talks with European Council president Donald Tusk.
But speaking before their scheduled talk, Mr Tusk firmly stated the deal and the backstop were "not open for renegotiation".
Brexit talks have all but stalled over the vexed issue of the Irish border - the most contentious aspect of any potential exit deal.
European Commission president Jean-Claude Juncker stuck to the same line, adding that Brussels still did not know what Britain wanted and that the chances of a 'no-deal' exit had increased.
Other EU governments backed that stance, leaving little room for Mrs May to realistically secure any changes to the Brexit deal.
Britain and the EU struck a divorce deal in November after a year-and-a-half of tense negotiations.
But the agreement has run aground in Britain's Parliament, which overwhelmingly rejected it on January 15.
Much of the opposition centres on the border measure known as the "backstop" - a safeguard mechanism that would keep the UK in a customs union with the EU to remove the need for checks along the border between Northern Ireland - under UK jurisdiction - and EU member, the Republic of Ireland, after Brexit.
Chief EU Brexit negotiator Michel Barnier said: "Frankly, no-one from either side is able to say precisely, in a clear way, what the nature of these alternative arrangements would be, whether they would be workable and effectively fulfil the aims of the backstop."
The EU Parliament's point-man on Brexit, Guy Verhofstadt, underlined that nobody in Europe wanted to use the backstop, but that it was, "needed to be 100 per cent sure that there is no border between Northern Ireland and the Irish republic".
Mr Verhofstadt said the only way for Mrs May to win concessions would be to back away from her long-held stance that Britain would not remain part of the EU's customs union after Brexit.
"If the future relationship is, for example, a customs union, that makes it completely different," Mr Verhofstadt told reporters.