Sam Gyimah, the universities minister, said “letting people decide now that people know more may be the most sensible path” as he announced he was quitting his post to vote against Theresa May’s deal.

“If we want to avoid chaos ... I would rather go down that path [a People’s Vote] than go down the path that would cripple our interests for decades to come,” Gyimah said.

And culture secretary Jeremy Wright admitted a second EU referendum was a “realistic alternative”, warning MPs that voting against the Government would result in either no deal “or we say to the British public ‘sorry, you have got it wrong. You are going to have to do it again’”.

Jeremy Wright floated a referendum re-run. Photograph: Getty

The admission came as parties at Holyrood revealed a motion opposing the Prime Minister’s Brexit deal that is set to be passed by MSPs on Wednesday.

The SNP, Labour, the Greens and the Liberal Democrats have said they will vote against the deal in a symbolic gesture to highlight Scotland’s opposition to the terms negotiated by the UK Government and to a no-deal Brexit. Their motion states “both a no-deal outcome and the outcomes arising from the Withdrawal Agreement and Political Declaration ... would be damaging for Scotland and the nations and regions of the UK as a whole” and proposes that “a better alternative be taken forward”.

In a joint statement, the parties said: “This debate will give the Scottish Parliament the opportunity to express its overwhelming opposition to both the Prime Minister’s Withdrawal Agreement and a no-deal Brexit, agreeing that a better alternative must be found.”

Ahead of a bilateral meeting on the fringes of the G20 summit in Buenos Aires, the Japanese Prime Minister Shinzo Abe gave May some badly needed good news when he endorsed the terms of the Brexit deal.

However, Abe also warned against a no-deal outcome that Japanese carmakers in the UK have said would put the future of their business at risk.

“I would like to take this opportunity to express my tribute to your leadership in realising the Withdrawal Agreement as well as the EU’s agreement on the Political Declaration,” the Japanese Prime Minister told May.

“Also I would like to once again ask for your support to avoid no deal, as well as to ensure transparency, predictability as well as legal stability in the Brexit process.”

There was also a boost for May at home where Penny Mordaunt, the international development secretary, offered her backing, having failed to endorse the Brexit deal publicly since it was agreed. “[The Prime Minister] has got my support,” she said.

Ministers admit second EU vote could happen if deal rejected