EU membership pledge key to a Labour-led government at next election, polling finds

A pledge to restore the UK’s EU membership could be the difference between a Labour-led government and a Reform-led government at the next election, new MRP polling finds.

A pledge to renew the UK’s membership of the EU was the only scenario tested that put the Labour Party within touching distance of forming a majority government at the next election, fresh MRP polling by YouGov with Best for Britain has found. 

The new seat-level MRP model assessed the impact of four hypothetical Labour policies on EU relations on Westminster voting intention, to estimate how it might affect the outcome of a General Election. It was carried out by YouGov across a sample of almost 14,000 GB adults and commissioned by Best for Britain. The four policies tested were: (1) seeking a closer relationship with the EU without rejoining the Customs Union, Single Market or the EU itself; (2) rejoining the Customs Union; (3) rejoining the EU Single Market; (4) rejoining the EU. The report also includes the results of a standard Westminster voting intention question.

Best for Britain layered additional analysis on top of the central estimates of YouGov’s constituency-level MRP projections to reflect the practicalities of a General Election (including tactical voting) and address the political and methodological limitations of hypothetical policy questions. 

The findings come as the government shapes its policy on Europe ahead of the heavily delayed UK-EU summit, the Labour Party’s conference in Liverpool, and Prime Minister Andy Burnham’s upcoming speech in which he is expected to set out his ten-year vision for the country. They also emerge as the first ministers of Scotland, Wales and Northern Ireland said the future of their nations belongs ‘in the European Union’.  

The data supports new Best for Britain research, also based on exclusive YouGov polling, which found that a clear manifesto commitment to full EU membership would secure the most support from the voters Labour needs to persuade to back them at the next general election. 

Key findings include:

• EU membership commitment could secure Labour 321 seats, only five less than the 326 needed for a majority government.
• In comparison, halfway scenarios such as the Single Market or Customs Union would see Labour win only 257/256 seats respectively, leaving them 70 seats short of an absolute majority. 
• If an election were held in June 2026 and Labour stuck to their current red lines on the EU (no return to Single Market, Customs Union, or Freedom of Movement), they could see their current 403-seat count slashed to 136 seats, resulting in a hung Parliament with Reform UK holding the highest number of seats and right-of-centre parties (Reform UK plus the Conservatives) having enough seats to form a coalition.
• A promise of EU membership could see Labour unseat key Conservative MPs including Leader of the Opposition Kemi Badenoch (North West Essex), Shadow Chancellor Andrew Griffith (Arundel & South Downs), and also Reform UK’s Robert Jenrick (Newark). 
• Labour’s national vote share could increase with an EU membership pledge to 37% according to YouGov central estimates, compared to baseline Westminster Voting Intention in June (18%) and under the current government approach, including the existing red lines (26%). 
• A more ambitious Labour policy on Europe does not increase voter support for the Conservatives or Reform UK. 
• Without Labour backing EU membership, they risk a near-total seat wipeout in Wales and Scotland. 
• Sticking to red lines could see Labour seats in Wales fall from 27 (current) to 5, and from 37 (current) to 3 in Scotland. 

Analysis of the central estimates showed that the more ambitious Labour’s policy pitch on EU relations, the better the party’s electoral performance at the next General Election is likely to be. All EU relationship options beyond the UK Government’s current red lines were found to increase Labour’s voting intention above Reform UK’s, rising to 37% of national vote share where Labour supported membership of the EU. Crucially, Labour moving to a more ambitious policy position did not result in an increase in support for Reform UK, or the Conservative Party. 

The more ambitious Labour’s policy position on EU relations, the fewer seats it was estimated to lose to parties on both its left and right flanks across the whole of Great Britain. In seats where Labour is facing Reform UK, by appealing to left-of-centre voters, an ambitious EU policy allowed Labour to outpace Reform UK, winning more contests. 

In seats where Labour is facing parties on its left flank, by appealing to left-leaning voters with a hypothetical EU membership commitment, it was able to push challengers into second place. The effect was most noticeable in Scotland and Wales, where Labour is facing a real possibility of being squeezed out of Westminster politics altogether. 

In Scotland, moving to a policy position of EU membership could result in Labour retaining between 27-32 of the 37 constituencies it won in 2024 (equivalent to up to 86%). An  EU membership policy scenario could result in Labour retaining between 19-24 of the 27 constituencies won at the last election in Wales. 

Campaigners are highlighting the political necessity of an EU membership pledge ahead of the next general election to secure a Labour-led government and keep Reform UK from holding the balance of power. 

Naomi Smith, Chief Executive of Best for Britain, said:

“These numbers are a wake-up call for both the Prime Minister and Labour backbenchers in previously Leave-voting constituencies. EU membership is the only policy lever that takes Labour close to a majority at the next election and keeps the architects of Brexit out of power.

“Labour’s electoral strategists must get their heads around the irony that seats they are most concerned about losing to Reform UK are less winnable if they pursue a low-ambition EU reset. Public opinion has shifted, a majority of voters in each seat support EU membership, and – crucially – are prepared to vote tactically to achieve it.”

“Our data shows that EU membership speaks directly to Labour’s target voters independently of other concerns. Floating voters, and those who have left the party for Reform UK or the Conservatives, are much more driven by the cost of living or the economy. The left voting bloc simply wants EU membership to become a reality.”

Tom Brufatto, Policy and Research Director at Best for Britain and lead author of the report, said: 

“These findings are the latest in a data series which clearly show that halfway houses will simply not do for voters, who want to return to Europe and all of the benefits it offers, or for Labour who are looking for manifesto entries.

“We have a Prime Minister who not only sees the damage caused by Brexit but the opportunity for his party to do things differently- that starts with a manifesto pledge to renew the UK’s membership of the EU.”