The Government is heading for a "hotch-potch" Brexit deal amounting to "leaving without leaving" which will not be acceptable to voters, former prime minister Tony Blair has said.
He suggested that public opinion may shift far enough to force a second referendum when voters are confronted with the reality that the deal they favour is "impossible".
Speaking to Bloomberg TV at the World Economic Forum in Davos, Switzerland, Mr Blair made clear he expected Labour's official position to move to support of continued membership of the European single market.
He suggested that, from that point, it would only be "a very short distance" to opposing Brexit altogether.
The former Labour premier said that preventing Britain's withdrawal from the EU will be possible only if there is a "clear" reversal of the public majority for Leave recorded in the 2016 referendum.
"There is nothing that would make me change my mind in thinking that this is a regressive move for the country," he said.
"But I think the country would proceed with Brexit if the Government succeeded in bringing forward a deal that retained the benefits of our single market membership without the obligations. It is just that I think that is an impossible thing to negotiate."
He added: "Will the public really shift in its position once it sees the deal the Government is bringing forward? We don't know.
"But if the deal is the one I suspect, which will be a hotch-potch where the Government tries to stay close to Europe and 'leave without leaving', I think it is going to be very difficult to persuade the British people that that is better than what we have now."
Mr Blair said he took "on face value" Labour leader Jeremy Corbyn's insistence that he is pro-Europe.
He added: "The Labour Party feels - for reasons I understand - that it's got to say 'We are still in favour of Brexit'. But when you see how the Labour Party is moving, it is moving very much towards a 'let's keep the single market' position.
"It nuances that in what it says, but I think in the end there is a majority within the Labour Party for keeping a close relationship with Europe.
"I think the moment you get to that position, it's a very short distance to the next position, which is to say 'let's not give up our seat at the decision-making table but still be the passive recipient of European rules'."
Mr Blair said Brexit was harming the country by distracting policy-makers' attention away from the key issue, to which they should be devoting "immense amounts of time and effort", of preparing Britain for the impact of transformative technological advances.