LONDON — After months of waiting, Boris Johnson has shown his hand.

The British prime minister on Wednesday proposed creating two new borders around Northern Ireland in a bid to break the Brexit deadlock with Brussels.

Johnson wrote to European Commission President Jean-Claude Juncker, insisting the entire U.K. should leave the EU customs union on the current Brexit deadline of October 31.

That would mean a customs border between Northern Ireland and Ireland, which Johnson said could be managed through electronic checks away from the border and physical checks at the premises of traders, as well as at other sites that could be located anywhere in Northern Ireland or Ireland.

But he said Northern Ireland should remain aligned to EU single market rules on agricultural products, as well as all other goods. That would mean a regulatory border between Northern Ireland and the rest of the U.K. and checks for goods crossing the Irish Sea.

“Both sides now need to consider whether there is sufficient willingness to compromise and move beyond existing positions to get us to an agreement in time" — Boris Johnson

The plan would be underpinned by the approval of the Northern Irish Assembly, which would get to vote on whether to keep the two-border arrangement or align more closely with U.K. rules — hardening the border with Ireland — every four years. The Stormont Assembly has been suspended for roughly two years, however, due to a political impasse in forming a government.

Johnson's proposals mark the culmination of weeks of talks with the EU, during which the U.K. has deliberately kept its position on the backstop alternative under wraps. Time is running out to strike a deal by the European Council summit on October 17 and 18.

Following the publication of the plan, Johnson spoke to Juncker by phone. In a statement, the Commission president acknowledged "positive advances," notably regarding the plan for Northern Ireland to abide by EU regulations. But he noted "some problematic points" and “concern” over the customs plan, and stressed that any solution must meet the EU's objectives of preventing a hard border in Ireland, preserving cooperation between Northern Ireland and the Republic, and protecting the EU's single market.

Irish Prime Minister Leo Varadkar said in a statement after his own call with Johnson Wednesday evening that “the proposals do not fully meet the agreed objectives of the backstop.” But he also said he would “study them in further detail, and would consult with the EU institutions,” as well as other EU27 leaders.

Varadkar said he “wants to see a deal agreed and ratified, and will continue to work in unity with our EU partners to this end.”

The EU27 and London are both keen to stress their commitment to finding a deal and neither will want to be seen as to blame should negotiations fail.

If the plan is rejected out of hand, Downing Street has said it will work on the assumption of a no-deal exit on October 31.

'Failure of statecraft'

According to an explanatory note published by the U.K. government, if Stormont does not consent to the new arrangement applying in Northern Ireland, “the arrangements will not enter into force or will lapse (as the case may be) after one year, and arrangements will default to existing rules.” It was not immediately clear which rules this refers to, EU or U.K.

The Democratic Unionist Party, which backs the Conservatives at Westminster via a confidence-and-supply deal, voiced support for the plan — despite long insisting it could not sign up to new regulatory checks between Northern Ireland and Ireland.

A statement from the party said: “This offer provides a basis for the EU to continue in a serious and sustained engagement with the U.K. government without risk to the internal market of the United Kingdom.”

The party insisted the plan would ensure that Northern Ireland would be outside the single market along with the rest of the U.K.

In his letter, Johnson said failure to reach a deal would “represent a failure of statecraft for which we would all be responsible,” adding: “Our predecessors have tackled harder problems: we can surely solve this one.

“Both sides now need to consider whether there is sufficient willingness to compromise and move beyond existing positions to get us to an agreement in time," he wrote. "We are ready to do that, and this letter sets out what I regard as a reasonable compromise: the broad landing zone in which I believe a deal can begin to take shape.”

Johnson will speak to Juncker on the phone on Wednesday afternoon, while top U.K. negotiator David Frost has been in Brussels explaining the proposals to his counterparts.

No more backstop

The proposals from the U.K. government are designed to replace the controversial backstop plan that was agreed between the EU and former Prime Minister Theresa May.

That would have seen the entire U.K. remain in a customs union with the EU until a solution could be found to manage customs checks across the Northern Irish border without the need for physical checks and infrastructure along the frontier.

Johnson said the checks envisioned under his new proposal would happen on a “decentralized basis” with paperwork done electronically and the “small number of checks needed” being conducted at the premises of traders or other points along the supply chain.

He admitted the plan would require improvements and simplifications to existing customs rules, which would have to be worked out between now and the end of the proposed Brexit transition period in December 2020 — a deadline that can be extended if necessary.

Johnson also promised a “new deal” for Northern Ireland that would include financial support to help manage the changes.

The prime minister said his proposals amount to a “meaningful Brexit” while protecting the Good Friday Agreement and respecting EU red lines.

A leaked version of a similar plan was approached with caution by EU leaders earlier on Wednesday.

Irish Prime Minister Varadkar had said before his call with Johnson that the leaked proposals did “not appear to form the basis for an agreement.” He plans to speak to Johnson again next week.

A spokesman for the EU’s chief negotiator, Michel Barnier, said earlier on Twitter that the European Commission would examine the U.K.’s proposal “objectively.” But he also made clear it is all but certain Johnson’s plan would be rejected, by reiterating the EU27’s long-standing demands, which include the prevention of a hard border on the island of Ireland and safeguarding the integrity of the EU’s single market.

Labour’s leader Jeremy Corbyn told Sky News the proposals are “worse” than what May had proposed because they could lead to U.K. regulations diverting from those of the EU.

“Quite clearly, if Northern Ireland is not in the [EU] customs union and it is supposed to be having open trade with the Republic of Ireland, you can’t do both things. There is a fundamental contradiction in what he is offering there,” he said.