Mass poll shows Labour wipeout across country · Eight cabinet ministers to lose seats · Tories would win majority of 146Ga by Hinsliff and Toby Helm The Observer, Sunday September 21 2008 Gordon Brown is set to lead Labour into an election bloodbath so crushing it could take his party a decade to recover, according to the largest ever poll of marginal seats which predicts a landslide victory for David Cameron. Eight cabinet ministers, including the Home Secretary and the Justice Secretary, would be swept away in the rout as the Tories marched into Downing Street with a majority of 146, says the poll, conducted for PoliticsHome.com and exclusively revealed to The Observer. Seats that have been Labour since the First World War would fall. The sheer scale of the humiliation is almost as bad as that endured by the Tories in 1997, suggesting it could take Labour a similar time to claw its way back to power. The party would be virtually extinguished in southern England and left with only its hardcore redoubts in northern England, the Welsh valleys and deprived inner-city areas. The stark findings from the survey of almost 35,000 voters across 238 seats, published on the PoliticsHome website today, are likely to fuel the stalled insurrection against Brown. A third of potential Labour voters in marginal seats would be more likely to back the party if he were replaced. Intriguingly, the findings also suggest David Miliband's hopes of leading Labour may depend on him challenging Brown before the election. While the Foreign Secretary would survive the rout, his power base would be decimated, making it much harder for him to get elected in a party likely to have shifted to the left: cabinet allies James Purnell and John Hutton would have gone, along with senior Blairites Alan Milburn and Charles Clarke. Jacqui Smith, Ruth Kelly, John Denham, Des Browne, Geoff Hoon and Jack Straw are projected to lose their seats. In Scotland, the poll predicts the SNP will win next month's Glenrothes by-election Yesterday as MPs gathered in Manchester for the annual party conference Brown began a fightback, pledging free part-time nursery places for two-year-olds in a move towards universal childcare for pre-school children. He told the Sunday Telegraph he wanted to see 'more choice for women and for families'. However, even as Brown was being cheered onto the conference stage, Clarke was urging MPs to confront him. In an article for the Sunday Times he said prevarication was 'actually the most dangerous course of all'. Today's poll shows how Labour's progressive face would be scarred by the projected defeat, with women disproportionately more likely to be defeated and five of its 13 black and Asian MPs, including three ministers, voted out. By contrast, Cameron's new intake would include a lesbian businesswoman, a 'chick-lit' novelist and a single mother turned farmer. He could claim he had transformed the Conservatives into a modern and multicultural party, potentially tripling the number of women in the ranks and adding five new ethnic minority and three openly gay MPs. It comes amid signs of clear momentum building behind Miliband, who uses an interview in October's issue of Prospect magazine - to be published during the conference - to attack the 'abuse of market power' by failing executives paying themselves unjustified salaries. The Foreign Secretary was also boosted when the Health Secretary, Alan Johnson, his biggest rival for the leadership, publicly ruled himself out and warmly praised Miliband. In a newspaper interview yesterday, Johnson praised his younger colleague's 'common touch', adding: 'I hope he goes a long way because I'm a big fan of his.' Brown now has a mountain to climb at a conference likely to be dominated by the twin threats of Miliband and the global banking crisis. MPs are being asked to sign a loyalty pledge circulated by the backbencher Martin Salter, while the star of The Apprentice, Sir Alan Sugar, has recorded a film urging critics to back the leader or 'have the balls to get out'.