BRUSSELS — European Union officials were astonished when British Prime Minister Boris Johnson this week claimed to be “encouraged by the progress” of critical, last-ditch Brexit negotiations.

Nothing is under negotiation, they said, because he has not bothered to make any suggestions.

Europeans listened to Johnson accuse the British Parliament of destroying his leverage by removing the threat of a no-deal withdrawal and pushing for another Brexit extension beyond the Oct. 31 deadline.

But Johnson undermined his own position by failing to follow through on promised proposals for discussion, they said.

After wild weeks of political trench-fighting in London, many Brexit policymakers in the E.U. capital of Brussels and around Europe say Johnson’s take-no-prisoners political approach has torpedoed what little remaining trust they had placed in him and in the British political system.

“Perhaps it’s for domestic use. But everybody reads the British papers,” said Anne Mulder, a Dutch lawmaker who leads Brexit planning in his country’s parliament. “He’s totally unrealistic. He’s saying if you don’t do what I say, I’ll commit suicide. There are no negotiations with this government.”

European officials are more than exasperated, according to nine diplomats and other officials who spoke on the condition of anonymity to discuss sensitive discussions.

When Johnson came to power in July, many Europeans expressed hope that he would be more adept than his predecessor, Theresa May, in getting Parliament to support a deal to manage Britain’s withdrawal from the trade bloc. Instead, Johnson has sought to sideline Parliament by suspending it for five weeks ahead of the Brexit deadline.

At the same time, he has told the British public that his Brexit negotiators have been hard at work — and making headway.

“I’ve been negotiating over the past five weeks to get us a new deal,” Johnson said in a video posted Thursday on Twitter. “E.U. leaders were willing to negotiate a new deal because they knew we were willing to leave on October the 31st, deal or no deal.”

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E.U. officials have denied offering a new deal — or even substantially amending the deal negotiated over two years with May.

Johnson’s primary objection is to the so-called backstop — a last-resort provision to prevent a hard border between Ireland and Northern Ireland and to maintain the commitments of the 1998 Good Friday peace agreement. In an Aug. 19 letter to European Council President Donald Tusk, Johnson wrote that the backstop, which would keep Britain closely tied to the E.U. for an indeterminate time, is “anti-democratic and inconsistent with the sovereignty of the U.K.”

Johnson promised German Chancellor Angela Merkel and French President Emmanuel Macron last month that he would come up with an alternative means to maintain an open border. He seemed earnest enough that the leaders came away thinking he did not want to leave the E.U. without a deal, according to advisers briefed on their assessments.

But Johnson has not yet come back with any ideas for how else to guarantee an open border, E.U. negotiators said.

His Brexit negotiator, David Frost, met with his E.U. counterparts on Wednesday for more than five hours. He proposed to strip away most of the backstop, leaving only a handful of bare-bones provisions, including borderless travel and a single electricity market, E.U. diplomats said.

The two sides met again Friday at Britain’s request. An E.U. diplomat said discussions focused on a British idea to avoid food safety controls on the Irish border.

E.U. diplomats have gotten the sense that continued talks are probably more for show than for substance. The lack of engagement by Johnson’s team on the core issues has led to puzzlement about his strategy. Does he genuinely want a deal but not have realistic ideas about how to get one? Or is it a bluff, and is he deliberately steering his country toward a Brexit without a safety net?

European policymakers increasingly say that the answer is the latter, and that they worry about being set up to take the fall.

One diplomat assessed that Johnson needs to pretend negotiations are underway so he can blame the E.U. for any fallout from a no-deal Brexit. But if Johnson negotiated in earnest, the details — and the compromises — would quickly become public, sapping support from hardcore Brexit advocates who are enthusiastic about leaving without a deal.

“As soon as the details of a deal leak, he’s going to lose the election,” the diplomat said.

Britain appears to be heading toward an early general election in coming weeks. Johnson is pressing for one ahead of a Brexit-focused summit of E.U. leaders that begins Oct. 17. He has argued that the British people should have their say on who represents them at the meeting. He boasted Friday that he would be able to secure a new deal there through his “powers of persuasion.”

But any agreement hammered out at the summit would almost surely come too late if Britain is leaving the E.U. on Oct. 31, European officials said. Both the British and the European parliaments would need to approve a deal, a process that is likely to take several weeks.

E.U. officials said that if Johnson — or any British leader — asked for an extension beyond the Oct. 31 deadline, he would almost surely receive one, if there was a clear rationale for it. Despite tough talk from Macron and others ahead of previous extensions this year, no E.U. leader wants to be responsible for the chaos that is likely to be unleashed by a no-deal Brexit, diplomats said.

The British Parliament has legislated to postpone by an additional three months. However, Johnson said Thursday he would “rather be dead in a ditch” than request further delay.

Even setting aside the uncertainty about events, there is deep skepticism in Europe that Johnson can be held to his word, and there are concerns about the health of Britain’s democracy.

“A lot of the bridges have been burned. There is a real feeling within the E.U. that Britain cannot be trusted, because the British system cannot be trusted,” said Fabian Zuleeg, the head of the European Policy Center, a Brussels-based think tank. “It is difficult to imagine that any commitment that is made by the leadership can be trusted, because we have seen in the last month how quickly that can change.”

The problem, European officials say, is that the British discussion still bears little relationship to the reality of what the E.U. is willing to agree to.

“Some members of the British Parliament are living in a fantasy world,” said Mulder, the Dutch lawmaker. “They want to be outside the European Union and keep all the advantages. Which is impossible. And if you live in this dream, then it is very difficult to negotiate, because it is not realistic.”

Quentin Ariès contributed to this report.

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