Britain’s return to the EU becomes more serious by the day

Senior Downing Street officials have contacted research and polling organisations as they seek to test public support for the United Kingdom rejoining the EU.

Aides to Andy Burnham have held talks with EU experts at a range of organisations about how the public would view a pledge to rejoin, as momentum grows for such a pledge to be included in Labour’s next manifesto.

Some in No 10 are keen to promise that Labour will negotiate at least re-entry into the bloc, something Burnham has previously said he wants to see happen “in his lifetime”. Others are concerned, however, that such a pledge could revive the political fortunes of Nigel Farage, the leader of Reform UK.

Burnham used his first speech at the Labour Party conference as leader to announce a review of the options for Britain’s relationship with Europe, and added on Wednesday that those options should also include full rejoining.

The prime minister told delegates on Tuesday: “Brexit has done more harm than good. So I will use the occasion around the [UK-EU] summit to explain to you, to explain to the country, what I believe are the different options for the long-term relationship of Britain with our European partners.”

On Wednesday, he clarified that this would also include the possibility of rejoining, something that had been ruled out by his predecessor, Keir Starmer.

Burnham told BBC Radio 4’s Today programme: “We can stay as we are. That is obviously an option, if people think that is the right place to be. We can look at what [former Conservative chancellor] George Osborne said about a customs union, we can look at what the Liberal Democrats said at their conference about the single market, or we can go all the way.”

Burnham’s comments sparked joy among pro-EU activists, who argue that rejoining is the best way to raise the UK’s growth rates, but also anger from political opponents.

Alex Burghart, the deputy leader of the Conservative Party, said: “Labour cannot blame a democratic vote from more than a decade ago for the consequences of their economic decisions.”

The Guardian has learned that Burnham’s comments are part of a broader effort by No 10 to test the consensus on rejoining, with a view to the possible inclusion of such a pledge in the next manifesto.

Officials have been in talks with several prominent research and polling organisations, which have worked on projects to flesh out the arguments on rejoining and to test public opinion.

Last week, the Tony Blair Institute published a paper arguing that Burnham should seek talks with Brussels on becoming a member again, but should do so only if Europe softens its regulations in sectors including energy and technology.

On the same day, the pro-EU campaign group Best for Britain published a YouGov mega-poll suggesting that Labour could double its number of seats if it went into the next election promising to rejoin.

In the coming weeks, the influential Institute for Public Policy Research will publish a paper calling for the country to rejoin, while Labour Together has also examined how difficult it would be to do so.

Some in Downing Street are encouraged by the polls, which show that a pledge to re-enter the bloc does not do much to raise support for Reform. They also point out that Farage attacked the prime minister’s speech for its pledge to change the pensions triple lock, rather than for his comments on Europe.

The Guardian has learned that some at the top of the government wanted the prime minister to use this week’s speech to promise to start work on rejoining after the next election, rather than to carry out a review.

In the end, such an option was ruled out because the party was already preparing for a battle over pensions and did not want to give Farage a boost, while he faces accusations of donations worth millions of pounds to his party.

No 10 said the prime minister had never considered making such a pledge in the speech and that it had not been included in any draft of it.

Some believe it would be difficult to persuade Brussels, which has been engaged in multiple rounds of talks about Britain’s relationship with the EU, to start negotiations on readmission.

But, in a major boost for rejoin supporters, Emmanuel Macron on Wednesday welcomed Burnham’s comments. “Welcome back”, the French president said in English during a press conference in Madrid on Wednesday.

He continued in French: “If the British want to come back and if the prime minister is moving in that direction, I think this is very good news, both for his country and for Europeans.”

An EU spokesperson said: “The United Kingdom is a close and valued partner of the European Union. It is for the government of the United Kingdom to determine how it wishes to develop its relationship with the EU in the future. We remain open to engaging on the options it may present.”

Burnham’s willingness to consider all options seems to have been accompanied by a new engagement on the EU’s “Made in Europe” legislation, which threatens to exclude UK goods from some supply chains on the continent.

No 10 has asked for British manufacturers to be classified as European for the purposes of this legislation, with officials threatening to delay a UK-EU summit until London receives signals that a deal may be possible.

However, since Burnham’s speech, there is now talk of holding the summit on November 20.

An EU diplomat said it was necessary for Starmer’s old reset agenda to be concluded before talks on “a true reset” began, confirming support for a UK-EU summit as soon as possible.

A second diplomat said there was “a good feeling” that Burnham was now considering all options and seeking a consensus, “something that Brussels has wanted to see”.