That would represent another economic shock - on top of the pandemic - that most economists think would affect Britain more.
Negotiators came to blows - albeit at a distance, due to coronavirus - when Mr Barnier's British equivalent, David Frost, said last month that the United Kingdom would not accept the EU's "low-quality" deal that no "democratic country could sign".
"And to tell the truth, this week there have been no real areas of progress".
"Our view of the political declaration is that, as it says in the title, it is a framework".
Round four of EU/UK trade negotiations after Brexit comes to an end.
Last month the UK's chief negotiator David Frost wrote to Barnier arguing that it was "not a provision any democratic country could sign".
Whether this is a reason to believe that there will be a no-deal, I am not so sure...
When pressed on whether he was standing behind the EU's opening position, Barnier appeared to concede that a "toolbox" would need to be devised for ensuring fair competition when it came to state aid. "October is too late for us".
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Ending talks would mean that when the transition period - which continues all European Union laws - finishes on December 31 there will be no replacement trade deal in place. But Mr Johnson has ruled this out. "Our door is still open to that end".
According to a report by the UK in a Changing Europe think-tank, the services sector which accounts for around 80% of the UK economy, has been largely missing from UK-EU trade negotiations which entered their fourth round this week.
The UK was "committed" to sticking to the political declaration, but the document had been created to set out only the "parameters" of discussions, they added, and was not a treaty. They continue to condition access to waters to an annual negotiation, which is not possible for us, not even technically possible.
"We are now at an important moment for these talks". If we are going to move this forward we are going to need face-to-face contacts and the ability to assess and understand better than we can do in this format, ' he said.
There is mounting concern among business - already hit hard by the fallout from the coronavirus pandemic - at the prospect of a "cliff edge" break to the UK's remaining access to the European Union single market with no new deal to replace it.
While an agreement is possible, German EU ambassador Michael Clauss insists London will have to show "a more realistic approach" to reach one by the end of the year.
The CBI business group called progress in the talks "worryingly slow, causing deep concern to firms when resilience has rarely been more fragile".