Labour MPs could trigger a Brexit nightmare for Sir Keir Starmer in 252 seats, new analysis conducted by GB News has revealed.
The People's Channel found almost two-thirds of Labour-held seats voted for Brexit in 2016, with just 157 supporting continued membership of the European Union.
Dozens of Labour MPs who represent these seats are part of the Labour Movement for Europe, which is putting pressure on the Prime Minister to forge closer ties with the Brussels bloc.
Three Labour MPs from Brexit-backing seats have already voted for the UK to rejoin the customs union, with Richard Burgon, Imran Hussain and Peter Lamb voting for a Ten Minute Rule Bill proposed by the Liberal Democrats.
However, an even bigger parliamentary test looms for Sir Keir.
The Liberal Democrats have vowed to table an amendment to the Prime Minister's EU reset legislation to force Labour to negotiate a customs union deal.
Graham Stringer, Labour's lone Brexiteer in the House of Commons, warned: “We certainly risk losing seats [to Reform UK] if it passes, and I suspect it might.
“What I see in my mailbox, from people who voted to leave the EU in 2016, is that this is about trust.”
Keir Starmer is poised to negotiate a further reset with the EU | REUTERSGB News's number-crunchers dissected how many seats could be included in a Brexit revolt by mapping on Leave support with the constituencies now poised to vote for Reform UK or the Conservative Party.
The overall figure shows Labour would lose 232 of its 252 Brexit-backing seats to Reform UK, with four being won by the Tories and another being picked up by Plaid Cymru.
Meanwhile, Labour would cling onto just 15 seats vulnerable to a Brexit revolt.
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Reform gains (232): Aberafan Maesteg, Aldershot, Amber Valley, Ashford, Ashton-under-Lyne, Aylesbury, Banbury, Barking, Barnsley North, Barnsley South, Barrow & Furness, Basingstoke, Bassetlaw, Bexleyheath & Crayford, Bishop Auckland, Blackley & Middleton South, Blackpool North & Fleetwood, Blackpool South, Blaenau Gwent & Rhymney, Blyth & Ashington, Bolton North East, Bolton South & Walkden, Bolton West, Bournemouth East, Bournemouth West, Bracknell, Bradford South, Bracknell, Bridgend, Broxtowe, Burnley, Burton & Uttoxeter, Bury North, Bury South, Bury St Edmunds & Stowmarket, Calder Valley, Camborne & Redruth, Cannock Chase, Carlisle, Castleford, Pontefract & Knottingley, Chatham & Aylesford, Chesterfield, Clwyd East, Clwyd North, Colchester, Colne Valley, Congleton, Corby & East Northamptonshire, Coventry East, Coventry North West, Crawley, Crewe & Nantwich, Darlington, Dartford, Dagenham & Rainham, Derby North, Derby South, Derbyshire Dales, Doncaster Central, Doncaster East & the Isle of Axholme, Doncaster North, Dover & Deal, Dudley, Dunstable & Leighton Buzzard, Easington, East Thanet, East Worthing & Shoreham, Ellesmere Port & Bromborough, Eltham & Chislehurst, Erewash, Forest of Dean, Folkestone & Hythe, Gateshead Central & Whickham, Gedling, Gillingham & Rainham, Gloucester, Gorton & Denton, Gravesham, Great Grimsby & Cleethorpes, Halifax, Halesowen, Harlow, Hartlepool, Hastings & Rye, Heywood & Middleton North, High Peak, Houghton & Sunderland South, Huddersfield, Hyndburn, Ipswich, Isle of Wight West, Jarrow & Gateshead East, Kettering, Kingston upon Hull East, Kingston upon Hull North & Cottingham, Kingston upon Hull West & Haltemprice, Lancaster & Wyre, Leeds East, Leeds South West & Morley, Leeds West & Pudsey, Leicester West, Leigh & Atherton, Lichfield, Lincoln, Lowestoft, Luton North, Luton South & South Bedfordshire, Makerfield, Mansfield, Merthyr Tydfil & Aberdare, Middlesbrough & Thornaby East, Milton Keynes Central, Mid & South Pembrokeshire, Mid Derbyshire, Montgomeryshire & Glyndŵr, Morecambe & Lunesdale, Neath & Swansea East, Newcastle-under-Lyme, Newton Aycliffe & Spennymoor, Normanton & Hemsworth, North Durham, North East Derbyshire, North East Hertfordshire, North Northumberland, North Warwickshire & Bedworth, North West Cambridgeshire, North West Leicestershire, Northampton North, Northampton South, Norwich North, Nottingham North & Kimberley, Ossett & Denby Dale, Penistone & Stocksbridge, Penrith & Solway, Peterborough, Plymouth Moor View, Plymouth Sutton & Devonport, Poole, Portsmouth North, Portsmouth South, Preston, Rawmarsh & Conisbrough, Redcar, Redditch, Ribble Valley, Rochdale, Rother Valley, Rotherham, Rossendale & Darwen, Rugby, Salford, Scarborough & Whitby, Scunthorpe, Selby, Sheffield Brightside & Hillsborough, Sheffield Heeley, Sheffield South East, Sherwood Forest, Shipley, Sittingbourne & Sheppey, Slough, Smethwick, South Derbyshire, South Dorset, South East Cornwall, South Ribble, South Shields, South West Norfolk, Southampton Itchen, Southend East & Rochford, Southend West & Leigh, Spen Valley, Stafford, St Austell & Newquay, St Helens North, St Helens South & Whiston, Stalybridge & Hyde, Stevenage, Stoke-on-Trent Central, Stoke-on-Trent North, Stoke-on-Trent South, Stourbridge, Sunderland Central, Swindon North, Swindon South, Tamworth, Telford, Thurrock, Tipton & Wednesbury, Torfaen, Vale of Glamorgan, Wakefield & Rothwell, Walsall & Bloxwich, Warrington North, Warrington South, Washington & Gateshead South, Watford, Welwyn Hatfield, West Bromwich, West Lancashire, Weston-super-Mare, Whitehaven & Workington, Widnes & Halewood, Wigan, Wolverhampton North East, Wolverhampton South East, Wolverhampton West, Wellingborough & Rushden, Worcester, Worthing West, Worsley & Eccles, Wrexham
Graham Stringer, a veteran Labour MP, warned Reform UK could benefit from backtracking on Brexit | GETTYTory gains (4): Hemel Hempstead, Middlesbrough South & East Cleveland, Reading & Mid Berkshire Reading West & Mid Berkshire, Uxbridge & South Ruislip
Plaid Cymru gain (1): Bangor Aberconwy
Labour holds (15): Alyn & Deeside, Bedford, Bootle, Bradford East, Caerphilly, Croydon East, Erith & Thamesmead, Feltham & Heston, Hayes & Harlington, Ilford North, Knowsley, Liverpool Walton, Middlesbrough South & East Cleveland, Newcastle upon Tyne North, Newport West & Islwyn,
GB News analysis also revealed Labour would currently win just 71 of its 157 Remain-supporting seats, losing 38 to Reform UK and 32 to the SNP.
Nigel Farage could hoover up support in Brexit-backing seats
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The Tories would claw back 11 and Zack Polanski's Green Party could snatch another five seats.
Reform UK MP Lee Anderson, who retained his seat of Ashfield following his defection from the Tories in 2024, told GB News: “Seventy per cent voted to leave the EU in Ashfield.
“Backing a customs union and a backdoor return to the EU would ensure Ashfield and the Red Wall are lost by Labour forever. It’s the ultimate betrayal.”
Julian Gallie, head of research at Merlin Strategy, also said Europe could become a major dividing line within Labour following the 2026 Local Elections.
He told GB News: “Polling suggests there is a growing appetite for rejoining the EU, particularly in Scotland, Wales and London, all of which have elections coming up in May.
“If Labour struggles, we can expect increased pressure from MPs in urban, Remain-supporting seats."