Europe's chief Brexit negotiator Michel Barnier has warned European politicians that he has no reason to be optimistic that Brussels and London will agree an orderly divorce.
Mr Barnier's stark assessment came as MEPs said there can be no Brexit deal without the backstop clause that Britain's Prime Minister Boris Johnson has demanded be stripped from any accord.
"I can't objectively tell you whether the contacts we have undertaken with Mr Johnson's government will lead to an agreement between now and mid-October," Mr Barnier told parliamentary group leaders.
Mid-October is when Mr Johnson would have to come to Brussels for a summit of EU leaders with either a new withdrawal agreement or a request for a delay to Brexit, but the British leader insists he would rather be "dead in a ditch" than postpone the 31 October withdrawal.
"We don't have any reasons to be optimistic," Mr Barnier said.
Next week, MEPs will vote in the Strasbourg parliament on a motion to reaffirm and reinforce the European negotiating stance - and place the blame for the stalemate in the talks firmly across the Channel in London.
"The resolution stresses a very clear message: you can't have an agreement without the backstop. It couldn't really be any clearer," David Sassoli, the speaker of the European Parliament told reporters in Brussels.
"The resolution says that if there is a no-deal departure, then that is entirely the responsibility of the United Kingdom," he added at a news conference after Mr Barnier's briefing.
Mr Barnier said he had received no plausible proposal from Britain as to how the backstop, a measure which sees Britain remain in the EU customs union until a way is found to keep the Irish border open, could be replaced.
"Regarding the talks we are still ready to examine objectively any concrete and legally operable proposals from the UK," he told reporters.
Mr Johnson's chief Brexit adviser, diplomat David Frost, was in Brussels yesterday and will return tomorrow for "technical talks" with Mr Barnier's team, but Number 10 continues to insist that the backstop must go before a deal is signed.
"The UK presented ideas in the areas of customs and manufactured goods and we had further exchanges on the political declaration," a UK spokesman said, as Britain continues to push alternative technical measures to govern border traffic.
Mr Johnson insists his goal is to reach a new withdrawal deal that would lay the groundwork for negotiating a future free trade agreement with Brussels, but that Britain must leave the bloc at the end of next month, come what may.
Many in Brussels doubt his sincerity and argue that, since Mr Johnson has lost his House of Commons majority and failed to convince the UK parliament to back a snap election, he may not be able to get any deal past his own MPs.
Mr Johnson nevertheless says progress is being made but, asked whether this is true, Green MEP Philippe Lamberts, a member of the Brexit steering committee, said: "No, it's not my sense but I guess he has to say that."
"He has to give the impression that he's negotiating in good faith. I think his whole plan is to take the UK out of the European Union without any deal but at the same time being in a position to blame the European Union for inflexibility," Mr Lamberts said.
One idea that has been circulating in press reports, and was cited by Mr Sassoli as possible, is to return to Mr Barnier's original concept of the backstop as a measure that would only apply to Northern Ireland, while England, Scotland and Wales leave the customs union.
Downing Street insists that Britain will not seek this - and Mr Barnier says he has received no proposals at all - but Mr Lamberts and Mr Sassoli suggested that it might be welcomed in Brussels.
"I think it is the most sensible option because it allows the mainland UK to still have full autonomy in terms of regulations and customs and yet it is a special treatment for Northern Ireland," Mr Lamberts told reporters.
"That to me, seen from my perspective, is a lesser difficulty than having the entire United Kingdom in such an arrangement."