The Brexit proposals put forward by British Prime Minister Boris Johnson constitute "progress" that finally opens up room for negotiations before the crucial European Union summit in two weeks' time, EU's Brexit negotiator said Wednesday.

However, the gap between both sides remains daunting and "to be frank, a lot of work still needs to be done" to meet the three key conditions of the EU, Michel Barnier said, after the United Kingdom offered the bloc a proposed last-minute Brexit deal and Prime Minister Boris Johnson urged the EU to hold "rapid negotiations toward a solution."

With the U.K. due to leave the bloc at the end of this month, Johnson said in a letter to European Commission President Jean-Claude Juncker that not reaching a deal would be "a failure of statecraft for which we would all be responsible."

He did not mention that the EU and the U.K. did reach a deal in 2018 — only for it to be rejected, three times, by Britain's Parliament.

The border on the island of Ireland remains the key sticking point, and the EU is insistent that it remain transparent and open — that any deal doesn't hamper the seamless economic co-operation between the EU's Ireland and the U.K.'s Northern Ireland and that any border deal respects the rules of the EU internal market.

"We will continue to work — to work to reach a deal. The 'no-deal' will never be the choice of the EU. Never," Barnier said.

'Final offer' to EU

The new proposals do focus on maintaining an open border between the U.K.'s Northern Ireland and EU member Ireland. The U.K. proposes to do that by keeping Northern Ireland closely aligned to EU rules for trade in goods, possibly for an extended period.

The proposals, and Johnson's letter, are being billed by Johnson's office as a take-it-or-leave-it "final offer" to the EU.

Johnson used a speech to his Conservative Party to implore the bloc to end more than three years of acrimonious wrangling over the terms of the U.K.'s exit from the EU.

"Let's get Brexit done," was the repeated refrain to delegates at the conference in Manchester, in northwest England.

British voters in 2016 narrowly chose to leave the EU but the country remains deeply divided over how to do it. In his speech, Johnson said people who voted for Brexit "are beginning to feel that they are being taken for fools."

Johnson warned of "grave consequences for trust in our democracy" if Britain did not leave the EU on the scheduled date of Oct. 31.

U.K. offering 'reasonable proposals'

He said the government was offering "constructive and reasonable proposals" to the EU in a plan that was a "compromise."

A Brexit agreement between the EU and Johnson's predecessor, Theresa May, was rejected by the U.K. Parliament, largely because of opposition to the backstop, an insurance policy designed to ensure there is no return to customs posts or other infrastructure on the Irish border.

An open border underpins both the local economy and Northern Ireland's peace process. But Johnson and other British Brexit supporters oppose the backstop because it would keep the U.K. tightly bound to EU trade rules in order to avoid customs checks — limiting the country's ability to strike new trade deals around the world.

On Wednesday, Johnson warned European Commission President Jean-Claude Juncker, seen here at the EU headquarter, that not reaching a deal would be 'a failure of statecraft for which we would all be responsible.' (John Thys/AFP/Getty Images)

Johnson insisted that "we will under no circumstances have checks at or near the border in Northern Ireland."

The proposal involves "an all-island regulatory zone on the island of Ireland, covering all goods." That would keep Northern Ireland in a regulatory zone with the EU for food, agricultural and industrial products, removing the need for checks.

That status would have to be renewed every four years by the Northern Ireland Assembly. However, that assembly has been suspended for more than two years by a dispute between the main Unionist and Nationalist power-sharing parties.

Under the plan there would still need to be customs checks, but Johnson suggested in his letter that they could be carried out away from the border at "other points on the supply chain," though he did not specify where.

The European Commission said in a statement that "we will examine [the U.K. text] objectively and in light of well-known criteria," which includes whether it prevents a hard border on the island of Ireland, preserves co-operation between the Republic of Ireland and Northern Ireland and respects the EU rules on trade across borders.

Johnson has vowed that Britain will leave on Oct. 31, with or without a Brexit deal.

In Wednesday's speech he repeated his contention that the U.K. can handle any bumps that come from tumbling out of the bloc without a deal, which would mean the instant imposition of customs checks and other barriers between Britain and the EU, its biggest trading partner.

A no-deal Brexit is "not an outcome we want … [but] it is an outcome for which we are ready," he said.

A Brexit slogan is displayed on a window at the venue of the Conservative Party's annual conference on Tuesday. (Phil Noble/Reuters)

But the U.K. government and businesses both say the disruptions would be substantial, with the flow of goods coming into Britain through the major Channel port of Dover cut in half.

Many lawmakers want to prevent a no-deal exit, and have passed a law that compels the government to seek a delay to Brexit if it can't get an agreement with the EU by Oct. 19. Johnson says he won't do that — although he also insists he will obey the law. He has not explained how doing both those things will be possible.