Sir Keir Starmer has been dealt a blow by the European Union over his plan to rewrite the Brexit deal.
The Labour leader pledged to seek a “much better” agreement with Brussels if his party takes power at the next general election.
But Brussels has played down the prospect of major changes to the Trade and Co-operation Agreement without rejoining the single market or customs union.
An EU source told The Times: “Unless Starmer is prepared to take a quantum leap and change Labour’s position on membership of the customs union then any renegotiation will really be not much more than a rebranding exercise.
“You could call it the Dover deal, but it will still work in the same way.”
A diplomat from a national government generally sympathetic to closer trade ties added: “Starmer does not want to rejoin the EU or the single market. It is not a big change in the UK approach, so why should the Europeans rethink everything?
“In terms of friction, the TCA works better for the EU and countries with trade ties to the UK than it does for the Brits. What is in it for us? What do we get?”
Labour has long been critical of the deal negotiated by the Tories under Boris Johnson, which is up for review in 2025.
Sir Keir, a Remainer who campaigned for a second referendum, has pledged to seek a closer trading relationship with the EU if he takes the keys to No 10.
Speaking to The Financial Times, the frontrunner to become the next prime minister said he would be pushing for a rewritten Brexit deal.
Sir Keir told the newspaper: “Almost everyone recognises the deal Johnson struck is not a good deal – it’s far too thin. As we go into 2025 we will attempt to get a much better deal for the UK.”
The Labour politician claimed he would not rejoin the customs union or single market.
He added: “I do think we can have a closer trading relationship as well. That’s subject to further discussion.
“We have to make it work. That’s not a question of going back in. But I refuse to accept that we can’t make it work. I think about those future generations when I say that.
“I say that as a dad. I’ve got a 15-year-old boy and a 12-year-old girl. I’m not going to let them grow up in a world where all I’ve got to say to them about their future is, it’s going to be worse than it might otherwise have been.
“I’ve got an utter determination to make this work.”
It comes as Sir Keir is in Paris today for talks with French President Emmanuel Macron, with post-Brexit relations expected to feature prominently.