Iain Duncan Smith is the latest top Tory to be targeted by a Remainer pact after the Greens bowed out of the race for his marginal seat and threw their weight behind Labour.
The two parties 'tactically' joined forces last night and will now train their guns on the Brexiteer ex-Conservative leader over the next month of general election campaigning.
It follows a Remain alliance brokered by the Lib Dems, Greens and Wales' Plaid Cymru in 60 seats where only one candidate will stand to avoid splitting the pro-EU vote.
Jeremy Corbyn has not officially signed up to this agreement, but yesterday's Green-Labour pact in Mr Duncan Smith's east London seat suggests that Remain parties are willing to informally team up to claim some senior Conservative scalps on December 12.
Iain Duncan Smith (pictured in Downing Street last month) is facing stiff Remain opposition in the election after the Greens withdrew from the race and threw support behind Labour
Faiza Shaheen, who will now get a clear run at unseating the ex-Conservative leader in his Chingford and Woodford Green seat, speaks at a rally in the constituency with Jeremy Corbyn
The Greens launch their party's general election manifesto in Bristol. But one of their candidates has now pulled out to form an alliance not sanctioned by the party
The Green candidate for Chingford and Woodford Green John Tyne said in a statement he was 'tactically withdrawing' from the Conservative-Labour marginal.
He made clear it was a deliberate move to unseat Mr Duncan Smith, who is defending his 2,400 majority in the constituency he has held since 1992.
Mr Tyne said: 'The actions of IDS as the architect of the failed rollout of Universal Credit mean that we believe he is unfit for office.
'The party believes that its withdrawal from this election offers the best chance for voters to register a concerted vote against him and his failed policy.'
Labour's Faiza Shaheen, director of a left-wing think tank and closely aligned to Mr Corbyn's politics, will get a clear run at ousting the former cabinet minister.
Reacting to the news, she said: 'So thankful to Waltham Forest and Redbridge Greens for standing aside in Chingford & Woodford Green and supporting me to #UnseatIDS.'
Mr Duncan Smith (middle) is a longtime arch-Brexiteer and was part of the hardline European Research Group which swung behind Boris Johnson's deal (pictured: far left, Steve Baker, second right, Mark Francois, far right, Sir Bill Cash)
Ms Shaheen, director of left-wing think tank CLASS is closely aligned to Mr Corbyn's politics and will get a clear run at ousting the former cabinet minister
Mr Duncan Smith was Work and Pensions Secretary for the majority of David Cameron's premiership, during which time he launched the government's Universal Credit benefits system, which has long been criticised by Labour.
The arch-Eurosceptic was part of the hardline group of Conservative backbenchers, the European Research Group, which swung behind Boris Johnson's Brexit deal after months of opposing Theresa May.
Although yesterday's pact will come as a blow to Mr Duncan Smith, he was given a boost when Nigel Farage announced he will not be fielding any Brexit Party candidates in current Conservative-held constituencies.
The slate of 317 Tory candidates who are contesting seats won by the party at the last election will be given a free run without the risk of the Brexit Party sapping votes from them.
However, as Mr Farage pointed out in a speech in Hartlepool yesterday, it is a 'unilateral' Leave alliance as the Conservatives are not standing down any of their candidates.
This contrasts with the pro-EU pact - struck by third-party campaign group Unite To Remain - between the Lib Dems and the Greens and Plaid Cymru.
Jo Swinson's candidates will be given a free run in 43 seats in England and Wales, where they hope their ardent Remain message will help unseat senior Boris Johnson allies such as foreign secretary Dominic Raab and one-time Tory leadership contender Jeremy Hunt.
The Unite to Remain group last week said that the Conservatives were 'worried' about their Remain Alliance snatching seats from some of their senior figures.
In 1992, Mr Duncan Smith stormed to victory in the east London seat by 15,000 votes, but since 2005, his majority has been slashed on each election.
The Waltham Forest Council borough voted 59 per cent to Remain in the 2016 referendum.
Mr Duncan Smith was Conservative Party leader between 2001-2003 (pictured as leader at the party conference in Blackpool)
The 60 seats where the Remain pact will unite behind one candidate
Bermondsey and Old Southwark - Humaira Ali
Buckingham - Stephen Dorrell
Chelmsford - Marie Goldman
Chelsea and Fulham - Nicola Horlick
Cheltenham - Max Wilkinson
Chippenham - Helen Belcher
Esher and Walton - Monica Harding
Finchley and Golders Green - Luciana Berger
Guildford - Zöe Franklin
Harrogate and Knaresborough - Judith Rogerson
Hazel Grove - Lisa Smart
Hitchin and Harpenden - Sam Collins
North Cornwall - Danny Chambers
North Norfolk - Karen Ward
Oxford West and Abingdon - Layla Moran
Montgomeryshire - Kishan Devani
Penistone and Stocksbridge - Hannah Kitching
Portsmouth South - Gerald Vernon-Jackson
Richmond Park - Sarah Olney
Romsey and Southampton - Craig Fletcher
Rushcliffe - Jason Billin
South Cambridgeshire - Ian Sollom
South East Cambridgeshire - Pippa Heylings
South West Surrey - John Wright
Taunton Deane - Gideon Amos
Thornbury and Yate - Claire Young
Totnes - Sarah Wollaston
Tunbridge Wells - Ben Chapelard
Twickenham - Munira Wilson
Wantage - Richard Benwell
Warrington South - Ryan Bate
Watford - Ian Stotesbury
Westmorland and Lonsdale - Janice Middleton
Winchester - Paula Ferguson
Witney - Charlotte Hoagland
York Outer - Keith Aspden
Brecon and Radnorshire - Jane Dodds
Cardiff Central - Bablin Molik
Brighton Pavilion - Caroline Lucas
Isle of Wight - Vix Lothian
Bristol West - Carla Denyer
Bury St Edmunds - Helen Geake
Stroud - Molly Scott Cato
Dulwich and West Norwood - Jonathan Bartley
Forest of Dean - Chris McFarling
Cannock Chase - Paul Woodhead
Vale of Glamorgan - Anthony Slaughter
Caerphilly - Lindsay Whittle
Carmarthen East and Dinefwr Dwyfor - Jonathan Edwards
Meirionnydd - Liz Saville Roberts
Ynys Mon - Aled ap Dafydd