British Prime Minister Boris Johnson confronted scepticism from across Europe on Thursday as he sought to muster support for his new approach to avoiding a messy divorce at the end of the month.
Johnson warned that the EU's refusal to accept his "final" offer would see it share the blame for the damage that might come from an unregulated end to the 46-year relationship.
The British government on Wednesday submitted its proposal for a new withdrawal agreement from the European Union to back up Johnson's vow to pull his country out of the bloc on October 31.
But EU Council President Donald Tusk said "we remain open but still unconvinced" the plan can preserve an open border between British-run Northern Ireland and EU-member Ireland after Brexit, a key point of disagreement.
The European Parliament's Brexit steering group also dismissed what it called "these last-minute proposals" as neither "credible (or) legally operable".
"The proposals do not address the real issues that need to be resolved," it said in a statement.
Johnson has until the end of the month to try to shore up support for a fresh approach to end the three-year political impasse since the Brexit referendum.
His inability to get everyone on board quickly would result in either a crash exit for Britain, despite worries over the potential economic damage, or a third Brexit delay this year.
Johnson reaffirmed on Thursday he had no intention of seeking an extension despite parliament's instruction to do so should he fail to secure a compromise over the next two weeks.
"We have shown great flexibility with our European friends," Johnson told lawmakers one day after publishing the details of his long-awaited plan.
"If our European neighbours choose not to show a corresponding willingness to reach a deal, then we shall have to leave on October 31 without an agreement -- and we are ready to do so.
"That outcome would be a failure of statecraft for which all parties will be held responsible."
- Bracing for the worst -
Businesses across Europe fear a "no-deal" Brexit could plug up long-established trade routes and unsettle financial markets for weeks and possibly months.
London stocks fell further Thursday as global growth worries were compounded by fears that Britain may be heading into recession just as it prepares to leave the European Union.
Irish Prime Minister Leo Varadkar said he was bracing for the worst.
"If we end up in a no-deal scenario, it may be the case that we have to live (with) no-deal for a period of time," Varadkar told reporters in Stockholm.
"Ireland will do what is necessary to protect the single market."
Johnson's strategy tackles the key Irish border issue by taking Northern Ireland out of the EU customs union but keeping it aligned with Ireland's rules and regulations for goods.
This would effectively create two temporary economic borders -- including one in the Irish Sea between mainland Britain and Northern Ireland.
One of the most contentious points of the deal gives the devolved Northern Ireland assembly the right to end its alignment with Ireland by 2025.
But a time-limited solution has been a deal-breaker for Brussels in the past.
UK Brexit minister Steve Barclay has noted that talks had to start by this weekend to stand any chance of securing a deal before EU leaders meets in Brussels on October 17-18.
"We need to move forward at pace, intensively," he told BBC radio. "All sides recognise that the alternative, no-deal, is disruptive."
- 'Half-baked' -
Johnson was reminded of the daunting challenges ahead when opposition parties lined up to denounce his proposals.
Labour leader Jeremy Corbyn called Johnson's plan "not workable" and "reckless".
The pro-European Scottish National Party's parliamentary leader Ian Blackford called the proposals "half-baked".
"Secure an extension or resign," he demanded.
Yet Johnson appears to have won vital backing from some members of parliament who had repeatedly rejected the deal his predecessor Theresa May struck with the EU in 2017.
These included at least four more moderate Labour members and some of the most ardent eurosceptics among Johnson's own Conservatives.
"It's got a very good chance of getting through," Johnson's no-deal Brexit preparations point man Michael Gove told ITV television on Wednesday night.
"It seems to be a pretty solid majority, and it's one that the EU can take reassurance from as well because one of the concerns that the EU had in the past (was that) look, if we make a concession, will it get through parliament?"