Mood in Brussels hardens amid growing doubts that PM that can get her deal voted through

Theresa May will face a wall of resistance when she returns to Brussels next week as the EU’s chief negotiator, Michel Barnier, declared her Brexit strategy had “failed” after another parliamentary defeat inflicted by hardline Eurosceptics.

May will insist to EU chiefs that her defeat in parliament on Thursday does not change her belief that her Brexit deal can still achieve a majority – as long as there are changes to the backstop.

The mood hardened in Brussels on Friday amid doubts that the prime minister could ever forge any consensus in her warring party, with Barnier telling diplomats from member states that her strategy could not work.

One EU ambassador has suggested the risk of a no-deal Brexit was as high as 90% given the prime minister’s intransigence.

The defeat in parliament came at the hands of the European Research Group, led by Jacob Rees-Mogg, who abstained on a government motion because it appeared to rule out a no-deal Brexit.

May, who will visit Brussels on Wednesday, is expected to insist that the group could still fall in line as long as necessary changes to the backstop are secured, pointing to the vote a fortnight ago on an amendment spelling out that “alternative arrangements” must be made.

However, Barnier told ambassadors May needed to now work cross-party to build support for the withdrawal agreement but had instead “widened rather than narrowed” the divide with the Labour leader, Jeremy Corbyn, in her response to his recent offer of support. He told diplomats that he “does not expect a solution this week”.

“The vote yesterday indicated there is no majority in the Tory party for the withdrawal agreement,” one diplomat said after Barnier’s address. “He said ‘strategy May has failed’ and that she needs to go cross-party.”

A number of ambassadors echoed Barnier’s reading. “We have a major problem,” one told the meeting.

Barnier, who will meet Corbyn on Thursday, also told diplomats that during a dinner with Stephen Barclay, the Brexit secretary, on Monday, the British cabinet minister had pressed the need for a legal guarantee of being able to exit the backstop or a time-limit on the customs union it envisages.

The EU official told the ambassadors that it appeared crucial to the government to be able to change the legal advice given by the attorney general, Geoffrey Cox. Cox is due to go to Brussels with Barclay on Monday.

Sources in London suggested the prime minister had hoped that other EU leaders would be more understanding of the kind of parliamentary game-playing seen on Thursday than officials in Brussels. “They are all politicians,” said a government source.

Privately, Downing Street is exasperated by what it regards as self-interested posturing by some MPs. Sources described the prime minister as furious in the voting lobbies on Wednesday night.

On Friday, May’s spokeswoman said the previous vote in January, where MPs passed an amendment demanding the backstop be replaced with alternative arrangements and rejected the possibility of no deal, was the only one that had spelled out what parliament would accept.

“The motion on 29 January remains the only one the Commons has passed expressing what it does want, and that is what we are pursuing,” the spokeswoman said.

Anger at the ERG’s antics was explicit from soft Brexit ministers in the aftermath of the defeat. The defence minister Tobias Ellwood called the group’s actions “selfish and provocative” and said they were acting as a “party within a party”.

Alistair Burt, the Foreign Office minister, gave his strongest signal yet he was prepared to resign unless the government allowed him to back efforts to stop no deal by the next vote at the end of February.

“If my colleagues cannot accept a necessary compromise, or if government does not itself move to prevent no deal, then I expect parliament to do so, as such moves would certainly pass a commons vote,” he said. “I will continue to act consistently with the views I have regularly set out.”

Senior Labour figures, including Keir Starmer and Jon Trickett, are to hold a fresh round of meetings with their government counterparts next week over whether a cross-party consensus can be found.

One person present at the last meeting said Barclay and May’s de facto deputy, David Lidington, appeared serious about looking for common ground – but that little progress was likely to be made until May is willing to lift her objection to a customs union.