British Prime Minister Boris Johnson sent European Commission President Jean-Claude Juncker a letter outlining his Brexit proposals | John Thys/AFP via Getty Images EU gives cautious response to UK’s ‘problematic’ Brexit plan EU27 officials suspect the prime minister’s offer is less about getting a deal, and more about positioning for an election.

Whatever Boris Johnson intended with his Brexit proposal, Brussels is sure of only one thing: The U.K. prime minister could not seriously expect them to agree to it.

Some are even seeing it as a declaration of war.

Johnson's push for sharp divergence from EU customs rules is interpreted by some in Brussels as not only closing off any chance of a deal on a Withdrawal Agreement but also as poisoning the negotiations of a future free-trade agreement before they even start. Even before Johnson had formally presented the plan to the European Commission, Irish Prime Minister Leo Varadkar stated that it "does not appear to form the basis for an agreement."

For many EU officials and diplomats, the most likely scenario is that the proposals are designed to elicit a swift rejection, so that Johnson can apportion blame to Brussels for the "failure of statecraft" that he referred to in his letter introducing the plans to Commission President Jean-Claude Juncker. They are especially irked that the prime minister's first detailed offer, put forward at the 11th hour, was also presented as his last.

"The letter doesn’t seem to be addressed to Juncker but first and foremost at British voters," said one EU27 diplomat. "These solutions require a big leap of faith."

Another EU official said, "It looks like he’s aiming at a no-deal but it’s unclear why. It seems he’s just going after new elections.”

Juncker and Johnson spoke by phone on Wednesday after the paperwork arrived from London, and in a statement the Commission reiterated its hope of reaching a deal, even as it said Juncker found some points in the British proposal "problematic." If Johnson was hoping for a hasty rejection that he could portray as Brussels intransigence, he didn't get it.

In its statement, the Commission said the EU welcomed progress in Johnson's call for "full regulatory alignment" for all goods entering Northern Ireland from Great Britain. That was one aspect of Johnson's proposal that somewhat echoed the backstop provision on the Ireland border already included in the Withdrawal Agreement, and that the EU has said is the only way to protect the integrity of its single market and protect peace on the island of Ireland.

But concerns remain about how it will work, not least because it relies on all traders playing by the rules. "The whole process increases the possibility of smuggling," one EU official said.

Separating regulatory and customs checks is a particular source of anxiety. "This proposal comes from the people who gave us BSE in 1996 and foot-and-mouth disease in 2001," said one EU diplomat referring to bovine spongiform encephalopathy, otherwise known as mad cow disease. “Our veterinarians still remember those risks very well.”

But where the backstop would maintain such alignment indefinitely, Johnson's plan envisions it lasting only for as long as the Northern Ireland Assembly and joint executive approve of it. Currently there is no joint executive, and the EU27 have said repeatedly that the backstop must be “all-weather” — that is, remaining in force until replaced by a deal on future relations.

"President Juncker welcomed Prime Minister Johnson's determination to advance the talks ahead of the October European Council and make progress towards a deal," the Commission statement read. "He acknowledged the positive advances, notably with regards to the full regulatory alignment for all goods and the control of goods entering Northern Ireland from Great Britain.

"However, the President also noted that there are still some problematic points that will need further work in the coming days, notably with regards to the governance of the backstop," the statement said. "The delicate balance struck by the Good Friday Agreement must be preserved. Another concern that needs to be addressed are the substantive customs rules. He also stressed that we must have a legally operational solution that meets all the objectives of the backstop: preventing a hard border, preserving North-South cooperation and the all-island economy, and protecting the EU's Single Market and Ireland's place in it."

The unwillingness of the Commission to reject Johnson's plan outright though highlighted an underlying concern that what is really taking place is not a negotiation toward an eventual deal on the U.K.'s departure, but a blame-game, in which each side is maneuvering to have the other held responsible for a failure to bridge the huge gaps in their positions.

To that end, the EU insisted that it would give the U.K. proposal serious consideration. "The EU wants a deal," the Commission statement said.

In Brussels, however, many officials have warned that there is extremely limited time before the October 31 deadline to negotiate the fine points of an entirely new and highly complex proposal.

Once negotiators conclude their talks, they would need to draft a new Political Declaration to be approved by EU member countries before the October European Council meeting, and any deal would then still need approval by all 27 remaining EU countries, as well as ratification by the U.K. parliament and the European Parliament.

And EU officials are not persuaded that Johnson will be able to find a majority in the House of Commons for any Brexit plan, given the bitter disagreements that have divided the legislature and the country ever since the 2016 referendum.

Johnson has already coaxed the EU to move from its previous position that the backstop is inviolable and the text of the Withdrawal Agreement unchangeable. As Juncker put it last month, he does not have an "emotional relationship" to the backstop, so long as its objectives are met.

But Johnson's forthright declaration that the U.K. seeks to diverge from EU trade and customs policy was seen as a particularly antagonistic departure from the negotiating stance of his predecessor, Theresa May. The idea that Britain would seek to become a fierce competitor — what some in Brussels refer to as Singapore-on-the-Thames — stands to complicate negotiations on a post-Brexit free-trade agreement.

And that could create something of a vicious circle for Johnson's hopes of removing the backstop. Its main purpose was to manage the border between Ireland and Northern Ireland in the event that a free-trade agreement has not been concluded by the end of the transition period. If a free-trade agreement seems less likely to come together quickly, the backstop seems even more essential to Brussels.

CORRECTION: This article has been amended to clarify how long regulatory alignment would last under the new proposal.