A letter signed by 80 opposition MPs, including shadow ministers, was sent to Corbyn and members of the shadow cabinet on Saturday and said a public vote should be the “bottom line” in the negotiations.
The letter warned any concessions secured in the cross-party talks – which have so far failed to produce a breakthrough – cannot be guaranteed, meaning a referendum is a necessary safeguard.
The missive said: “Theresa May has been clear that the legally binding part of the Brexit deal, the Withdrawal Agreement, cannot be renegotiated.
“This means that the only concessions Labour could obtain will be non-binding assurances about the future relationship. Any future Tory prime minister could simply rip up these ‘guarantees’ after Theresa May leaves office, and it is the stated aim of the vast majority of Tory MPs to do precisely this.
“The only way to guarantee jobs, rights and protections – and Labour’s reputation with its membership and the electorate – is to support a confirmatory public vote on any option which is agreed by parliament, which will put additional pressure on the government to hold the early general election the country needs.”
The letter was organised by the Love Socialism Hate Brexit campaign and signatories include shadow treasury ministers Clive Lewis and Anneliese Dodds, shadow minister for disabled people Marsha de Cordova and shadow science minister Chi Onwurah.
The letter added: “Any compromise deal which is now agreed by parliament will have no legitimacy if it is not confirmed by the public.
“The views of members are clear. Labour’s democratically established policy, passed at [the party’s] conference in September 2018, is to oppose a Brexit deal which does not meet Labour’s six tests and put any deal that does to a public vote.
“It would be untenable for Labour not to insist on a public vote on a deal which did not meet these tests.”
Labour is deeply split over the issue of a second referendum, with a letter signed by 25 MPs on Thursday arguing against another public vote.
They warned it would “divide the country further and add uncertainty for business” and could be “exploited by the far-right, damage the trust of many core Labour voters and reduce our chances of winning a general election”.
Corbyn said on Saturday that he was waiting to see the government change its position on the withdrawal deal. “I haven’t noticed any great change in the government’s position so far,” he said. “I’m waiting to see the red lines move.”