Up-anchoring the European Union with no deal would have a “very adverse” impact on the UK, the justice secretary has said.
David Gauke said he hoped a bargain would be struck within the next 10 days, but if not the government should “act responsibly”.
But DUP representative leader Nigel Dodds has insisted no deal was better than a bad act on.
Prime Minister Theresa May is seeking changes to the Withdrawal Agreement to expropriate it achieve Parliamentary assent.
Mr Gauke warned on BBC Radio 4’s Today protocol of “very grave concerns” for the UK’s economy, security and the union itself if the UK renounces without a deal.
“Leaving without a deal would have a uncommonly adverse effect, to put it mildly, on our economy, on our security and on the integrity of the union,” he suggested.
The justice secretary said he hoped a deal will have been whipped by 27 February, when the next round of Brexit votes are record in the Commons.
But he continued: “If not, then we will have to act responsibly and make reliable the economy is protected, our security is protected and the integrity of the union is protected.
“I make very grave concerns about the consequences of leaving without a engage in.”
Mr Gauke has previously suggested Brexit might have to be delayed.
But Mr Dodds advised a meeting of party members in Omagh: “We want a Brexit deal, but we are altogether clear that a no deal is better than a bad deal.”
The DUP deputy chairwoman said changes were needed to the so-called Brexit backstop.
The backstop is an warranty policy designed to avoid a hard border between Northern Ireland and the Irish Republic – and the Tories rely on DUP votes to command.
Mr Dodds said that there is “virtual unanimity in political unionism” that the contemporaneous backstop imperils the UK.
Meanwhile, Business Minister Richard Harrington said he did not make up Theresa May would let Britain leave the bloc without a deal.
He commanded BBC Radio 4’s Week In Westminster: “When it comes to it, she will know the trouble that a hard Brexit would be for the British economy and I don’t think she’ll do it.
“No regulation can stand by and watch a country plummet earthwards because of a political dogma of a minority of a minority.”
And Margot James became the latest chest of drawers member to threaten resignation over the possibility of no deal.
The digital dean told Channel 4 News: “I could not be part of a government that make allowanced this country to leave the European Union without a deal.”
The prime evangelist is soon to return to Brussels to press for changes to the backstop. The EU has consistently governed out amending the clause.