British ministers are divided over the government's next steps if Prime Minister Theresa May's Brexit deal with the European Union is not approved by parliament next month.
With just under 100 days until Britain is due to leave the EU on March 29, deep divisions in parliament have raised the chances of leaving without a deal and increased calls for a second referendum to break the deadlock.
Work and Pensions Secretary Amber Rudd said late on Wednesday there would be a "plausible argument" for another referendum if parliament failed to reach a consensus on the way forward, something May has repeatedly ruled out.
House of Commons leader Andrea Leadsom said a so-called people's vote would be unacceptable and that a "managed" no-deal would be an alternative.
May pulled a vote on her deal from parliament earlier this month after admitting it would be defeated.
She is seeking "assurances" from EU leaders over the so-called Irish backstop, an insurance policy to avoid a hard border between the British province and EU-member Ireland that its critics fear will trap Britain in a customs union with the EU indefinitely.
May's spokesman said a second referendum was not plausible and that the EU had been a clear a "managed" no-deal was not available. The prime minister was focused on getting the assurances parliament wants on the backstop, he said.
Leadsom later told parliament that several days of debate ahead of that vote would begin on Jan 9.
May has repeatedly said that if her deal is rejected then the world's fifth-largest economy might have to leave without a deal - the nightmare option for big business - or that Brexit might be thwarted altogether.
Some ministers have indicated they would quit the government if the no-deal option became official policy.
Earlier this week, the government said it would implement plans for a no-deal Brexit in full and begin telling businesses and citizens to prepare.
Meanwhile, Britain's House of Commons erupted into outrage and near mutiny on Wednesday over an alleged sexist jibe by the opposition leader against Theresa May.
After months of warring over Brexit, MPs in the governing Conservative Party were united in condemnation of Labour leader Jeremy Corbyn, who was accused of muttering that May was a "stupid woman".
But Corbyn said he had used the words "stupid people", referring not to May but those "seeking to turn a debate about the national crisis facing our country into a pantomime".