Britain could rejoin the European Union as an "associate member" under the bloc's expansion plan set up by France and Germany.
The UK would be expected to contribute to the EU's annual budget and be governed by the European Court of Justice in exchange for "participation" in the bloc's single market.
The plan will be officially announced on Tuesday afternoon when Sir Keir Starmer, leader of the Labor Party, meets Emmanuel Macron, the French president, in Paris.
Sir Keir said he would prioritize securing “a much better deal for the UK” in the post-Brexit trade deal review, expected in 2025, if he wins the election next appointment.
Brussels is preparing to welcome Ukraine as a full member of the bloc in less than seven years, in the biggest shake-up in decades. Top EU officials have set a 2030 deadline for enlargement, including the Western Balkans and the biggest reforms to the EU's budget and electoral system since the 2007 Lisbon Treaty.
Paris and Berlin will present their vision for the bloc on Tuesday on the sidelines of a ministerial meeting in Brussels.
Laurence Boone and Anna Luhrmann, the Europe ministers of France and Germany, will propose a four-tiered structure to integrate countries that aren’t “willing and/or able to join the EU in the foreseeable future”.
Under the plan, Britain could be invited into the third tier as an “associate member” of the EU.
“Associate members would not be bound to ‘ever closer union’ and further integration, nor would they participate in deeper political integration in other policy areas such as justice and home affairs or EU citizenship,” a report commissioned by France and Germany says.
“The basic requirement would be the commitment to comply with the EU’s common principles and values, including democracy and rule of law,” the report reads. “The cost areas of participation would be the single market.”
The EU internal market is built on four key freedoms: movement of people, goods, capital and services.
The contribution will be lower than the usual member-wide contribution, but will result in "lesser benefits", such as no access to the EU's common agricultural fund.
Associate members will be represented by speakers in the Commission and the European Parliament without any voting rights.
The trade and cooperation agreement signed by Boris Johnson ended the jurisdiction of the European Court of Justice in the UK and ended the UK's financial contributions to the bloc.
“Countries would join one or the other outer tier out of their own political will, either because they withdraw from the EU or because they have no intention of joining in the first place,” according to the Franco-German plan.
“Careful negotiations will be needed to find the right balance between a looser form of integration and institutional participation while retaining the highest benefits for full EU member states.”