Final Say: Justine Greening backs The Independent's campaign for Brexit deal referendum

Justine Greening has said the prime minister’s Brexit plan is “already dead” and called for politicians to take their heads of out the sand, as she backed The Independent’s campaign for a second referendum.

The Tory former education secretary said Theresa May’s Chequers agreement would lead to a “disastrous decade of continuing division” and instability as it lost the support of the public, the Conservative Party and even members of the cabinet.

She said that many MPs, including senior Conservative ministers, agreed that a new vote may be the only way to break the Brexit deadlock, as Theresa May’s wafer-thin parliamentary majority leaves her vulnerable to hardliners on both sides.

It comes after The Independent launched its Final Say campaign for a public vote on whatever Brexit terms emerge, which garnered the support of more than 350,000 people in its first few days.

Ms Greening, writing for The Independent, said: “The difficult truth is that the prime minister’s Chequers deal is already dead. It’s time we stopped pretending otherwise.

“It doesn’t have the support of the public, my party or even those ministers who spent two years negotiating on behalf of Britain. Parliament is at stalemate and the sooner we deal with it the better.

“The prime minister should finish her EU negotiations, but it’s inconceivable that in our democracy any government could then believe it was sensible or right to press ahead with its route on Brexit without knowing it had clear public support, especially when all the indications are it does not.”

She added: ”It is an unacceptable state of affairs and must change ... A referendum on the final deal is the only responsible course ahead.”

Ms Greening wants three options on the ballot paper – the prime minister’s deal, Remain or a no-deal Brexit – to solve the impasse, amid speculation Ms May will be unable to get her deal through parliament.

She said: “A parliament that works on party political lines has failed to deal with a Brexit that cuts across all of that.

“Brexit has been the parliamentary equivalent of putting diesel into an unleaded car and it’s broken the engine.

“The result of that is that our parliamentary democracy is rapidly approaching a crisis unless we find a way to deal with this.”

The campaign was launched with a major editorial on Tuesday, which said: “The British people decided to pursue our course in the referendum of 2016, so as we now look for a decision on whether we will like the deal agreed with the EU (assuming there is one), it is natural that those same people should have the final say.

“Indeed, given the magnitude of the decision, it would be essential for the British people to be given that final right of approval, even if cabinet and parliament were providing the leadership we need, which they are not.”

It has attracted a swell of support from senior politicians across the political divide, including former prime minister Tony Blair, Tory ex-attorney general Dominic Grieve and Liberal Democrat leader Sir Vince Cable.

Anti-Brexit campaigner Gina Miller has also shown her support, along with NUS vice president Amatey Doku, who declared: ”Students are with you”.

It comes after Ms May’s efforts to bypass Brussels was rebuffed by EU leaders, when she and her senior ministers attempted to win backing for her Brexit blueprint through a series of diplomatic visits.

The EU’s Brexit negotiator, Michel Barnier, also poured cold water on the customs proposals that form a key plank of her white paper.

The prime minister received a boost when Austria agreed that Brexit would be among topics for discussion at an informal meeting of EU leaders in September.

However, she faced challenges closer to home as the chairs of several cabinet ministers’ constituency associations told The Sunday Telegraph that they opposed the Chequers plan or would remove their support if further concessions were given to Brussels.

Her own chairman, Richard Kellaway, initially said the plans must not be “diluted”, but later gave a statement where he said the Maidenhead branch fully supported the prime minister’s plans.