A No 10 source says a Brexit deal is “essentially impossible” after a call between the PM and Angela Merkel.
Boris Johnson spoke to the German chancellor earlier about the proposals he put forward to the EU – but the source said she made clear a deal based on them was “overwhelmingly unlikely”.
They also claimed she said a deal would never be possible unless Northern Ireland stayed in a customs union.
Mrs Merkel’s spokesman said they did not reveal confidential conversations.
The President of the European Council, Donald Tusk, sent a public tweet to Mr Johnson, writing: “What’s at stake is not winning some stupid blame game. At stake is the future of Europe and the UK as well as the security and interests of our people.”