Theresa May was battling on Sunday night to save her Brexit deal and prolong her premiership, amid signs Eurosceptics could move against her if there is a delay to leaving the EU.
The prime minister’s position looked precarious as she was unable to announce any progress in talks with the EU less than 48 hours before her House of Commons vote on the deal.
One Downing Street insider said the week ahead looked “choppy” as parliament is likely to vote to extend article 50 and rule out a no-deal Brexit if MPs do not approve May’s withdrawal agreement with the EU.
Two former cabinet ministers – Nicky Morgan and Dominic Raab – suggested that her premiership would be in trouble in that scenario, with speculation that Eurosceptics will try to force her out.
To avoid that threat, May will need votes in the week ahead from about 100 Tory and Democratic Unionist party Eurosceptics, who want an assurance that the UK will not indefinitely be bound by the Irish backstop and a permanent customs union with the EU.
In a last-ditch effort to win over the rebels, ministers were discussing whether the prime minister could even offer to name a departure date if it would help the deal to pass, while Philip Hammond, the chancellor, was preparing to offer billions to “end austerity” in the spring statement.
Jeremy Hunt, the foreign secretary, also warned Eurosceptics that failing to back May’s deal meant there was “a risk and a possibility that we end up losing Brexit in the next couple of weeks”.
But hardline pro-Brexit supporters were holding their nerve and insisting they would still only consider backing a deal if Geoffrey Cox, the attorney general, has changed his mind about the permanent nature of the backstop.
Steve Baker, a leading figure in the European Research Group, said: “I am clear a change of prime minister would not create an escape from the backstop unless the new prime minister were willing and able to breach international law. And that is absolutely not who we are as a fair-dealing UK.”
To those warning of a threat to Brexit, he said: “The people who would stop Brexit should know just this: what you do, you’ll have to do in public now. Stopping Brexit will be on you, not Brexiteers. Don’t kid yourselves otherwise.”