LONDON (AP) — British Prime Minister Boris Johnson sought Thursday to build a coalition at home to back his fresh Brexit approach even as key European leaders declared that the measures he just proposed fall far short of the concessions needed to forge a deal.

Johnson offered a strikingly more conciliatory tone than his previous tempestuous appearances in the House of Commons, arguing that changes his government just proposed on regulating trade between Ireland and Northern Ireland after Brexit represented significant compromise. Johnson thinks the concessions should resolve the concerns that prompted British lawmakers to reject the previous Brexit deal three times.

“We have made genuine effort to bridge the chasm, to reconcile the apparently irreconcilable and to go the extra mile as time runs short,’’ he said.

Britain is set to leave the EU on Oct. 31 unless it seeks an extension and one is granted. Johnson has said he plans to leave on that day with or without a Brexit divorce agreement, yet the British Parliament has passed a law requiring him to seek an extension if no deal is reached. It’s not yet clear how Johnson can reconcile that directive with his plans to leave the EU.

The new proposals from Johnson’s government focus on maintaining an open border between the U.K.’s Northern Ireland and EU member Ireland _ the key sticking point to a Brexit deal. 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.

As the day wore on, however, key EU figures expressed ever more skepticism over the new U.K. proposals.

Irish leader Leo Varadkar told reporters the new Brexit plans “fall short in a number of aspects,’’ while the European parliament supervisory Brexit group issued a damning verdict, arguing that the new proposals “do not match even remotely” what is needed for a compromise.

After being briefed by EU Brexit negotiator Michel Barnier, the Brexit group declared that the proposals were a step back towards an overall deal. The group unites experts from all major groups in the European Parliament, which must approve any final Brexit deal.

British voters narrowly chose to leave the EU, but the country remains deeply divided over how to do it. Johnson has warned of “grave consequences for trust in our democracy” if Britain doesn’t leave the EU on the scheduled date of Oct. 31.

The UK prime minister reached out Thursday to the EU and to the House of Commons with a softer tone, despite the fact the proposals were once been billed by Johnson’s office as a take-it-or-leave it “final offer.” Johnson sought mightily to lower the temperature of the heated debates that have characterized exchanges in recent weeks _ commenting that he was “disappointed’’ by the tone used by other lawmakers sharply questioning his proposals.

Unrepentant British lawmakers attacked the Brexit plan and Johnson, accusing him of proposing a deal he knows won’t work. The Scottish National Party’s parliamentary leader, Ian Blackford, said Johnson's proposals simply push the country closer to a no-deal Brexit by offering a plan that the EU is likely to reject.

“These proposals are unacceptable. They are unworkable. They are undeliverable, and it's all about blaming someone else _ in this case the European Union when the plan was rejected,’’ he said. “Mr. Speaker, it is a plan designed to fail, but of course, the prime minister knows that. By his own desire, this take-it-or-leave-it threat is yet another push towards a catastrophic no-deal Brexit."

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

The U.K. proposal doesn’t put a time limit on that status, though it 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 they could be carried out away from the border at “other points on the supply chain.”

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Casert reported from Brussels. Greg Katz in London and Jan M. Olsen in Copenhagen contributed.