Boris Johnson has claimed to have made a "genuine attempt to bridge the chasm" to strike a fresh Brexit deal with the EU - but the bloc has said it is “sceptical” about the “repackaging of old ideas”.
He said his proposals do not deliver all his departure desires but insisted they are better options than to "remain a prisoner" of the current situation.
However, the EU has already poured cold water on his proposals with the European Commission describing the potential deal as “problematic”.
European Parliament Brexit co-ordinator Guy Verhofstadt told BBC Radio 4’s World At One on Thursday: “We scrutinised the proposals that have been put forward by the UK Government and we are very sceptical about it because again it is repackaging old ideas that have already been discussed in the past.
“We have serious doubts about the seriousness of these proposals because today a memo was leaked, a memo sent by Downing Street to Tory MPs to immediately blame the European Union.“If such a document has really been sent to the Tory MPs you can have doubts about the seriousness of these proposals.”
A spokesperson said it was up to the UK to find a solution, adding: “We are not going to be the ones left holding the bag, the ball, or any other kind of object.”
Irish Tanaiste Simon Coveney has already shot down the plans, saying the government in Ireland cannot support any Brexit proposals that suggest a minority in Northern Ireland could make decisions for the majority.
A number of EU officials have also expressed concern that Mr Johnson is aware his proposed deal will not be accepted by the EU and will use their rejection to force through his no-deal agenda.
Mr Johnson has said he wants an agreement in place for the EU summit on October 17, but also admitted today that the two sides are "some way from a resolution".
Johnson lays out his plan
Mr Johnson urged MPs to “come together in the national interest behind this new deal”.
“This government's objective has always been to leave with a deal and these constructive and reasonable proposals show our seriousness of purpose,” he said, acknowledging they are a compromise.
"So we have made a genuine attempt to bridge the chasm, to reconcile the apparently irreconcilable and to go the extra mile as time runs short."
He said he had "constructive" calls with European Commission President Jean-Claude Juncker, German Chancellor Angela Merkel and Irish premier Leo Varadkar.
Mr Johnson is preparing for 10 days of "intensive discussions" as he seeks backing from EU leaders.
What has the EU said?
European leaders have been careful not to rubbish the plan on sight, but have nevertheless signalled their concerns amid concerns the resumption of customs checks could upset the careful balance of the Good Friday agreement which guaranteed an open border.
European Commission spokeswoman Natasha Bertaud said: “We have many questions on the text.”
She added: “We have pointed out that there are problematic points so, yes, we have questions and these need to be answered by the UK and not the other way around.”
The European Parliament's Brexit steering group is also said to have "grave" concerns about the proposals, according to Sky News.
European Commission President Jean-Claude Juncker said elements of the plan were "problematic" while Irish premier Leo Varadkar said it did not "fully meet the agreed objectives" of the backstop.
Others were more outspoken, with Guy Verhofstadt, the European Parliament's spokesman on Brexit, saying his response was "absolutely not positive", while Sinn Fein expressed outrage that the DUP would effectively be given a veto over the plan in the Assembly.
Speaking in the Commons this morning, Jeremy Corbyn said the plan amounted to a "rehashed version of previously rejected proposals that put the Good Friday Agreement at risk and would trigger a race to the bottom on rights and protections for workers, consumers and our precious environment.”
He said: "Given the seriousness of this issue and the vagueness of the proposals so far, can the Prime Minister tell this House if and when he plans to publish the full legal text that he must submit to the EU?”
He added: "No Labour MP could support such a reckless deal that will be used as a springboard to attack rights and standards in this country."
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What about the Tories?
Mr Johnson, has however, appeared to have secured support from large swathes of Tory MPs.
Steve Baker, the chairman of the European Research Group of hardline Tory Brexiteers, signalled he could back the deal, while the DUP was making positive sounds, as was Labour's Stephen Kinnock, who is key in cross-party efforts to leave with a deal.
But their stances could well alter if Brussels insists on changes, as seems likely.
In his letter to EC President Juncker, Mr Johnson said the proposals were "entirely compatible" with the maintenance of an open border between Northern Ireland and the Republic.
Mr Johnson's allies in the Democratic Unionist Party (DUP) - which has a majority in the Northern Ireland Assembly - have broadly welcomed it.
Arlene Foster, the leader of the DUP, described the proposals as a "serious and sensible way forward".
What’s in the revised plan?
Under the UK proposal, Northern Ireland would effectively remain tied to EU single market rules through the creation of an all-Ireland "zone of regulatory compliance" for trade in manufactured goods and agri-foods.
That would mean for regulatory purposes goods - including foods and livestock - could continue to flow across the border, although there would be some documentary checks for those being traded between Northern Ireland and the rest of the UK.
However, the UK - including Northern Ireland - would leave the customs union, allowing it to seek trade deals with other countries.
The government acknowledges this would mean some physical customs checks on goods traded between Northern Ireland and the Republic, but says they would only apply to a "very small proportion" of trades and would take place well away from the border.
Under the plan, the arrangements would kick in in 2021 at the end of the proposed transition period.