Brexit talks have ended in stalemate once more amid warnings negotiations should not be allowed to drag on until Christmas.
Top Tory Michael Gove raised hopes that the tense dispute over post- Brexit trade for Northern Ireland can be resolved without tearing apart Boris Johnson's deal.
But talks between Brexit Minister Lord Frost and his EU counterpart Maros Sefcovic failed to achieve a breakthrough on Friday.
Both sides have dialled down their bullish rhetoric but Lord Frost said that "significant gaps" still remain - despite EU concessions.
He described the talks as "intensive and constructive", adding: "There is the potential to generate some momentum in our discussions."
But the Brexit Minister warned "significant gaps remain across most issues", and said a "significant change from the current situation" is required.
The UK wants to overhaul a key part of the Prime Minister's deal known as the Northern Ireland Protocol, which effectively keeps Northern Ireland in the EU's single market to prevent a hard border on the island of Ireland.
Instead an Irish Sea trade barrier was created, which has led to red tape and delays for businesses in Northern Ireland.
Lord Frost said the option of triggering Article 16 - which would suspend parts of the post-Brexit arrangements - remains on the table.
But he noted that some progress had been made discussions around access to medicines.
Mr Sefcovic said: "It is essential that the recent change in tone now leads to joint tangible solutions in the framework of the protocol."
He added there is a "genuine urgency" to resolve the issues of medicines flowing from Great Britain into Northern Ireland.
"We now need to press on and get this crucial issue across the line," he said.
But he restated his position that the protocol could not be renegotiated - and the trade deal was intrinsically linked to the PM's Brexit agreement.
Earlier, Mr Gove said the UK was "confident" that progress could be made without triggering Article 16 of the Northern Ireland Protocol, which allows the UK or the EU to temporarily abandon commitments made in the agreement.
The Cabinet Minister told a summit in Cardiff: "I do believe that there is a constructive approach that's being taken by the Commission and Lord Frost has signalled that while, of course, it's always possible that Article 16 may require to be invoked, we're confident that we'll be able to make progress without it."
Taoiseach Micheal Martin urged the PM to step back from threats to trigger Article 16 - but he suggested that the "mood music" had changed.
He told the BBC : "Where there is a will, there is a way, and I think both sides just need to knuckle down and get it resolved."
He urged both sides not to "leave it to Christmas Eve this year" after negotiations ran until December 24 in 2020.
