Labour could trigger years of chaos if its new leader tries to get Britain back into the European Union, Kemi Badenoch warned today. The Conservative leader lashed out as the governing party turned on itself over whether to undo the result of the 2016 referendum.Wes Streeting yesterday sparked a new front in Labour's civil war by setting out his desire for a 'new special relationship' with Brussels and to eventually rejoin the trade bloc.It prompted a furious backlash from allies of Andy Burnham, who like Mr Streeting covets replacing Sir Keir Starmer in No10 in a leadership battle this summer.Lisa Nandy said that the former health secretary risked 'reopening the Brexit wars' with his 'odd' call yesterday for the country to rejoin the bloc, ten years after the seismic vote to leave. But Mr Burnham, the Greater Manchester mayor, yesterday said there was a 'long-term case' for rejoining, even though he does not want to raise it as an issue, as he seeks to win a by-election in Makerfield, a heavily Leave-backing area of Wigan. Mrs Badenoch told Sky News's Sunday Morning With Trevor Phillips: 'The country wants us to make the best of Brexit, make the best of leaving the EU.'The idea of starting again, going backwards, having all of these negotiations, this is a sign of the Labour Party that does not have a plan for the country, so they want to go back and refight wars, which were settled a long time ago.'She added: 'It's not going to be as simple as walking through a door. It's going to be years more of negotiations, years more of the country not being governed.' The Conservative leader lashed out, as the governing party turned on itself over whether to undo the result of the 2016 referendum Lisa Nandy said that the former health secretary risked 'reopening the Brexit wars' with his 'odd' call yesterday for the country to rejoin the block, ten years after the vote to leave Mr Streeting sparked a new front in Labour's civil war yesterday as he set out his desire for a 'new special relationship' with the EU, and to eventually rejoin the trade blocThe Culture Secretary, who posted pictures on social media of herself out campaigning with Mr Burnham yesterday, attacked his leadership rival while ostensibly on TV representing Keir Starmer's Government.Mr Streeting sparked a new front in Labour's civil war yesterday as he set out his desire for a 'new special relationship' with the EU, and to eventually rejoin the trade bloc.Speaking at the Progress think tank's conference in central London on Saturday, Mr Streeting described Brexit as a 'catastrophic mistake', and broke the ice on a topic which Labour has long avoided revisiting.'We need a new special relationship with the EU, because Britain's future lies with Europe – and one day back in the European Union,' he said.But speaking to Sky News today, Ms Nandy said: 'I think it is a bit odd, if I am honest.'She added: 'The Government that he was part of until recently has been trying to take a far more pragmatic approach to bringing us closer to Europe and repairing some of the damage that was done from a poor Brexit deal to people's living standards in parts of the country like mine, rather than reopening the Brexit wars and going round back again around that track.'Ms Nandy added: 'If rejoining the EU is the answer, then essentially what we're saying to people is 'life was fine in 2015, we just need to go back there'.'I know Wes is coming up to campaign in the by-election quite soon. He will hear loud and clear from people in places like Wigan, Ashton, Winstanley, across Makerfield, that that is absolutely not the case. And the answer has to be bigger.'And she stopped short of endorsing the PM staying on in No10, saying he had to 'make up his own mind' about continuing. Ms Nandy posted pictures of herself with Mr Burnham and fellow ally Louise Haigh yesterday, saying it was 'lovely to see some good friends come over to help'Join the discussionCould the EU row sink Streeting before he even starts?What's your view?The policy offer could also be read as a direct challenge to Mr Burnham, who has previously expressed support for rejoining the EU, but may wish to avoid directly speaking about the issue as he bids to become Labour's candidate in the upcoming Makerfield by-election.The constituency on the edge of Greater Manchester was a Brexit-voting area in the referendum held nearly ten years ago, on June 23, 2016.Ms Nandy posted pictures of herself with Mr Burnham and fellow ally Louise Haigh yesterday, saying: 'Good to be out on the doors in Winstanley today and lovely to see some good friends come over to help.'Reform UK, whose leader Nigel Farage was among the most prominent supporters of leaving the EU, won every council ward in the Makerfield constituency in last week's local elections, securing around half the vote, while Labour won only a little more than a quarter.The Manchester mayor is also pro-Europe but will not want any focus on the issue as he tries to win a by-election in the Makerfield constituency – which voted 65 per cent for Leave in 2016 – as he embarks on his own leadership challenge.And on Saturday, Mr Burnham already appeared to be on the back foot over the key issue when he was asked by ITV News if he was in favour of rejoining the EU.The mayor, who has previously said he hopes the UK will rejoin 'in my lifetime', replied: 'I've said in the long-term there is a case for that, but I'm not advocating that in this by-election.'Mr Streeting's remarks were described by Government sources as 'divisive' and 'pure, selfish ambition', while Mr Farage told the Daily Mail: 'The North will be lost to Labour forever.'Labour MP Josh Simons, who announced on Thursday that he would give up his seat to make way for Mr Burnham to return to Parliament, said the party should 'come together' to back him.He told the BBC's Laura Kuenssberg: 'If Andy wins the by-election, my view is that the different bits of the party should come together behind Andy.'Asked if that would mean 'the end of Keir Starmer', Mr Simons responded: 'By implication, yeah.'