The new British Foreign Secretary Dominic Raab has criticised the European Union over what he claims is a "stubborn" approach to the Irish backstop.
He says the UK will leave the EU without a deal unless the EU changes its position.
It comes as the British cabinet meets to step up preparations for a no-deal Brexit.
Mr Raab says the UK still wanted to strike a "good" new deal with the European Union - but claimed the "undemocratic" backstop must be scrapped.
"It's not just about the UK's position, it's about what the EU decides."
"The message has already been sent out immediately that there is a deal to be done if the EU will shift on this crucial issue."
Asked about consistency in the EU's approach to the backstop, Mr Raab says: "They've been pretty stubborn throughout and Brexit is a decision taken by the UK people as one in a referendum.
"And the response to Brexit by the EU will be something that they'll need to take responsibility for".
The backstop, agreed to by former British Prime Minister Theresa May and the EU, is essentially an insurance policy to avoid the return of a hard border on the island of Ireland.
But opponents object to it because it would mean Northern Ireland continuing to follow some EU rules and regulations.
Mr Raab revealed that the UK government is "working on the assumption" that the UK will leave the bloc without a deal on October 31st.
The country's new Prime Minister Boris Johnson has promised Britain will leave the EU on October 31st, with or without a deal.
And he has made it clear that any new deal struck with Brussels must not include the backstop.
New British committees have been set up to ensure Brexit is delivered by the October deadline.
A daily operations committee will gather every weekday, with the first meeting on Tuesday.
While an exit strategy committee will meet twice a week - and its next meeting on Thursday will be chaired by Mr Johnson.
A third committee has also been established - the exit, economy and trade committee.
Mr Johnson has said the UK must "renew the ties" between its four nations ahead of a visit to Scotland on Monday.
