Those backing another referendum include senior figures from all the major parties, such as former Tory cabinet minister Justine Greening, ex-prime minister Tony Blair, Liberal Democrat leader Vince Cable, and Green leader Caroline Lucas.
The Independent kicked off its campaign for a Final Say on whatever Brexit terms emerge, along with a petition, earlier this week.
Ex-cabinet minister Ms Greening said: “I believe that putting the final decision on Brexit in the hands of the British people is the only way to break parliament’s impasse, and the right way to decide our country’s future.
“That’s why The Independent’s campaign is so vital and has my support – anyone who feels the same should back it.”
Sir Vince said: “The Liberal Democrats have been fighting for the British people to have the final say on any Brexit deal, or worse still, no deal. This vote must include an option for an exit from Brexit.
“I congratulate The Independent for joining this campaign. It’s both a brave and correct move.”
Ms Lucas said The Independent’s voice was "already making a huge impact".
Chuka Umunna and John Rentoul debate the possibility of another Brexit referendum
Labour MP David Lammy, who has called for a second referendum since 2016, said: “The Independent’s new push for a referendum on the final Brexit deal sits, with other similar campaigns, on the right side of history.
“Allowing the public to choose whether we remain in the EU – or indeed choose, in full knowledge, to become poorer, less sovereign and diplomatically neutered – is the only democratic solution to this political nightmare.”
Former Conservative attorney general Dominic Grieve, Labour’s Chuka Umunna, Lib Dem MP Layla Moran, campaigner Gina Miller and ex-Labour spin doctor Alastair Campbell have also backed the campaign.
Theresa May has urged voters not to worry about Brexit, despite her government setting out plans to stockpile food, blood and medicine in case it goes badly.
She said people should take “reassurance and comfort” from news of the plans, to be implemented if the UK crashes out of the EU without an agreement in March.
Brexit casualties
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But as a no-deal Brexit began to look more likely, Mr Blair took to Twitter to give his support to the campaign.
He said: “33m+ people voted in the EU referendum wanting a better country, not to be poorer, not to put further pressure on our already stretched health service, not for job losses or to stockpile food and medicines. It should be your #Finalsay.”
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