Theresa May was dealt a humiliating blow on Thursday as EU leaders dismissed her flagship Chequers proposal and sent her back to the drawing board.
In a dramatic day in Salzburg, European Commission President Donald Tusk plunged the knife into the UK's Brexit offer, saying bluntly: "It will not work".
The EU leaders gathered in Austria for the informal summit were unmoved by a plea from May to allow the UK to stay tied to Brussels' rules on goods, but diverge on services.
German Chancellor Angela Merkel and French President Emmanuel Macron also spoke out against the proposal as the EU27 put on a united front against the UK.
Tusk cast doubt on a special Brexit summit pencilled in for November, saying if sufficient progress towards a deal wasn't made in the next four weeks that meeting would not go ahead.
In a press conference just minutes after Tusk publicly shot down her plan, a visibly angry May called on the EU to put a counter-offer on the table that would keep the border between Ireland and Northern Ireland "frictionless".
After the interventions, former Brexit Secretary David Davis urged the Prime Minister to abandon her plan and pursue a free trade deal in keeping with the one struck between Canada and the EU.
Another Tory MP, Remain-backing Grant Shapps, called on May to withhold the UK's £39billion 'divorce' settlement if no deal was reached.
Tusk delivered his damning assessment of the Chequers proposal after EU27 leaders over a working lunch. He then had a face-to-face conversation with May, which she described as "frank".
Reflecting on the position of the EU27, Tusk said: "Everybody shared the view that while there are positive elements in the Chequers proposal, the suggested framework for economic cooperation will not work. Not least because it risks undermining the Single Market."
His comments were supported by Macron, who described Chequers as "not acceptable", and Merkel, who vowed their would be "no compromises" when it comes to the Single Market.
The other stumbling block remains the 'backstop' plan for the Ireland/Northern Ireland border if no trade deal is agreed by the time the UK leaves the EU.
Brussels believes the UK plan to use technology to keep the border frictionless is undeliverable, and instead wants Northern Ireland to effectively stay in the customs union and Single Market. May has said "no British Prime Minister could accept" such a plan as it would undermine the integrity of the United Kingdom.
As EU leaders lined up to demand more compromises from the UK, May tried to pile the pressure back on Brussels.
Speaking at a press conference in a sweltering room which left the PM visibly sweating, May reiterated that any proposal for the Irish border "cannot divide the United Kingdom into two customs territories".
She added that the UK would be "bringing forward our own proposals shortly" for a new backstop.
Turning to the future trade deal, May said: "There is no solution that will solve the Northern Ireland border which is not based on the frictionless movement of goods.
"Our white paper remains the only serious and credible proposition on the table for achieving that objective."
Brexiteer Conservative MP Simon Clarke said: "Tory MPs across the spectrum will hope this is the moment where Chequers is indeed chucked."