The European commission also refused to go into the secretive and intensive “tunnel” talks with the UK’s negotiators before a crunch summit on 17 October from which the UK had hoped to deliver a breakthrough deal.
Despite concerted attempts to avoid publicly trashing the UK proposals, there was dismay behind the scenes in Brussels after Johnson tabled his first concrete proposal for replacing the Irish backstop.
The prime minister had set out the outline of the government’s offer in a speech to Tory party faithful in Manchester that also laid down the battle lines for a general election. On Wednesday night, he was hopeful a parliamentary majority could be assembled to back it.
Johnson’s plan involves Northern Ireland leaving the EU’s customs union at the end of transition along with the rest of the UK, necessitating checks and controls on the island of Ireland.
Northern Ireland would also stay aligned with EU standards on goods if Stormont agreed by December 2020, the end of the transition period, and then in a vote every four years.
But the UK has also requested that both sides commit at treaty level “never to conduct checks at the border” even if Stormont vetoes the arrangements laid out in the new 44-page Irish protocol.
Barnier said that this commitment would prevent Brussels from protecting its internal market if the Northern Ireland assembly blocked the arrangement in 2020 or at a later date.
“The EU would then be trapped with no backstop to preserve the single market after Brexit,” he warned, according to someone present in the room.
The Irish taoiseach, Leo Varadkar, issued a sombre statement after a phone call on Wednesday afternoon with Johnson. Varadkar warned the prime minister that the legal texts tabled “do not fully meet the agreed objectives of the backstop”.
Jean-Claude Juncker, the European commission president, told the prime minister in his phone call that there remained “problematic points”.
It is understood that the European parliament’s Brexit steering group will say on Thursday that MEPs will not vote in support of the deal proposed by the UK government. “The reaction of the Brexit steering group was not positive,” the group’s coordinator, Guy Verhofstadt, told reporters after a briefing from Barnier. “Not positive in that we don’t think really there are the safeguards that Ireland needs.”
EU sources said that such were the flaws in the UK’s proposals that there appeared scant chance of agreement by a crunch EU summit on 17 October. “Unfortunately we are heading for an extension,” said one diplomatic source. Under the Benn act, Johnson will be instructed to request and agree an extension if a deal is not passed by parliament by 19 October.
In his speech in Manchester, the prime minister attacked parliament for seeking to block Brexit, repeatedly praised the NHS and warned the EU27 that he was determined to take Britain out of the EU on 31 October.
He sought to ramp up the pressure on Brussels by insisting Britain is now ready to leave without a deal at the end of this month. “That is not an outcome we want, it is not an outcome we seek at all – but let me tell you, my friends, it is an outcome for which we are ready,” he said.
He then asked the packed hall in Manchester: “Are we ready for it?” The audience shouted back: “Yes!”
On a carefully choreographed day, more details of his five-point Brexit offer were then laid out in a letter to Juncker, in which he warned there is now “very little time” left in which a deal can be done.
“This government wants to get a deal, as I’m sure we all do. If we cannot reach one, it would represent a failure of statecraft for which we would all be responsible,” Johnson said.
Johnson said the plan was a “fair and reasonable compromise”, and talked of a “broad landing zone, in which I believe a deal can begin to take shape”.
He added: “There is very little time … We need to get this done before the October European council.”
Johnson has won the support of the Democratic Unionist party, which has been closely involved in discussions about the plan in recent days.
Ministers believe the DUP is the “canary in the coalmine”, whose objections to Theresa May’s deal helped to kill it with the pro-Brexit European Research Group (ERG).
They hope the DUP’s approval will help to win over many of those Conservatives who rejected May’s deal. Steve Baker, the ERG chairman, tweeted that Johnson was a “hero” after his conference speech, signalling his approval for the PM’s approach.
With the DUP, and the eurosceptics of the European Research Group on board, Johnson also appears within touching distance of assembling a parliamentary majority for the plan.
May’s Brexit plan fell apart when MPs rejected it three times, and No 10 believes the EU leaders may be more persuadable if they believe a deal could pass through parliament.
Jeremy Corbyn dismissed Johnson’s proposals. He said: “It’s worse than May’s deal. I can’t see it getting the support that he thinks it will get.”
Speaking to Sky News, the Labour leader said Johnson would create a Britain of deregulation and of undercutting, adding: “It will also undermine the Good Friday agreement.”
Asked how it was worse than May’s proposals, he said “particularly the section on Northern Ireland” and “a specific intention to deregulate alongside Europe”.
Corbyn urged Johnson to come to the Commons on Thursday to explain his plan, adding that Labour would be telling him it was “not acceptable”.
The Scottish first minister, Nicola Sturgeon, was similarly unimpressed, tweeting: “Hard to see how the UK government Brexit ‘proposals’ fly. And hard to escape conclusion that they’re designed to fail.”
Government sources said either Johnson or Steve Barclay, the Brexit secretary, would make a statement to MPs.
Parliament is then expected to be suspended on Tuesday, to allow the government time to prepare for a Queen’s speech on 14 October, setting out what Johnson calls the “people’s priorities”.