David Miliband has called for a second referendum on Brexit and urged politicians on all sides to fight back against the "worst consequences" of the EU referendum vote.
The former Labour Foreign Secretary described the outcome of the 2016 referendum as an "unparalleled act of economic self-harm" driven by "the politics of grievance".
Mr Miliband said: “Britain is suffering its own governability crisis. Leaving the EU was mis-sold as a quick fix. Now it looks like a decade-long process of unscrambling the eggs of national and European legislation”.
In an intervention which puts him at odds with Jeremy Corbyn, the Labour leader, he said the country should have the chance to vote on any Brexit deal in a second referendum with a straight choice between remaining in the EU and the negotiated alternative.
He also describes Philip Hammond, the Chancellor, as "valiant", saying his support for a Brexit transition deal is "vital".
In an article for the Observer he said: "People say we must respect the referendum. We should. But democracy did not end on June 23 2016. The referendum will be no excuse if the country is driven off a cliff.
"MPs are there to exercise judgment. Delegating to Theresa May and David Davis, never mind Boris Johnson and Liam Fox, the settlement of a workable alternative to EU membership is a delusion, not just an abdication."
In his article, Mr Miliband stopped short of following the former Conservative aide James Chapman in calling for pro-Remain MPs to come together in a new party.
He did however back cross-party calls - supported by Conservatives Lord Hague and Heidi Alexander and Labour's Stephen Kinnock - for Britain to remain in the European Economic Area free trade zone along with Norway, Iceland and Lichtenstein as well as the EU member states.
"In Britain, the implementation of the EU referendum decision has been rash and chaotic. The timing and content has been governed by factions in the Tory party. Our negotiating position is a mystery - even on immigration," he wrote.
"So the fightback against the worst consequences of the referendum has the opportunity and responsibility to get its bearings fast."