Ed Miliband in battle after union threat over "Blairite dead" ED MILIBAND is facing one of the most bitter rows of his leadership at this week's Labour conference, after the leader of the UK's largest trade union vowed to seize back control of the party and force out the "Blairite dead." Len McCluskey, general secretary of Unite, which has bankrolled Labour with £6 million in the past two years, said he would use the union's political muscle to purge the remaining supporters of Tony Blair and New Labour, such as the party leader's brother David. Ed Miliband hit back, insisting that Unite would not be allowed to dominate the party despite being its biggest financial backer, in a row that threatens to become one of the biggest rifts in recent years between Labour and the unions at the annual conference. The party leader said "there is no future for this party as the party of one sectional interest of society," and warned union bosses that any attempt to shift policies to the left would lead to a heavy defeat at the next general election. Mr Miliband dismissed a demand from Mr McCluskey to abandon Labour's backing for pay restraint in the public sector, despite a threat from the union leader to withdraw financial backing for some of the party candidates. He said: "We've got the right policy to say we put jobs in the public sector ahead of pay rises. That's what we said we would do this parliament. It is a difficult decision but it is the way to keep jobs in the public sector. There is no future for this party as one sectional interest of society. We must be the party of the private sector just as much as the party of the public sector. Former deputy Labour leader Lord Prescott also stepped into the row on the opening day of conference in Manchester yesterday, telling Mr McCluskey to "grow up." The clash threatens to overshadow the leader's keynote speech to conference delegates tomorrow. Mr Miliband is expected to set out the latest attempt to broaden Labour's appeal and win back supporters who deserted the party at the 2010 general election. Mr McCluskey told the Labour leader to "kick the New Labour cuckoos out of our nest" and reconnect with unions such as Unite, which backed him in a bitter leadership contest two years ago with his brother. He warned Unite would only offer financial support to Labour candidates who backed its stance on issues such as strikes over UK government policies. Mr McCluskey went on to say his members were "furious" with what he claimed was the Labour leadership's "crazy" backing for pay restraint. He also confirmed that Unite had a strategy to "reclaim Labour" by persuading 5,000 trade unionists to join the party by the end of the year, to increase pressure within constituency parties to select "union-friendly" candidates for the next election Asked if the union's strategy could be viewed as plot to seize control of the party, Mr McCluskey said: "Of course we are trying to influence the party again." He said: "It is a question of us having to go to our activists and get them to join the Labour Party. We are trying to win Labour back for our core values: a belief in collectivism, in fairness, justice, equality, decency and respect, and to kick the New Labour cuckoos out of our nest. He has got to reject the siren voices that come from the Blairite dead because the truth is they offer no hope for the future. Some unions believe those on the right of the party remain too influential and want backers of the controversial New Labour pressure group Progress, founded in 1996 by former business secretary Lord Mandelson, to be expelled from Labour. However, Mr Miliband rejected the union leader's call for a purge of supporters of Mr Blair and insisted he was "not for pushing people out of the Labour Party. I want more people in the Labour Party. Mr Miliband defended Labour's links with the trade unions, claiming that the relationship "at its best it puts the party in touch with working people." Lord Prescott, a former union shop steward, heavily criticised Mr McCluskey's attack on Mr Blair's Labour governments, in which the peer served as deputy prime minister. He said: "I can't understand people saying "the Blair era was bad." Even to Len McCluskey I'd say, "More of your people were in work in the areas where we need them, in public services, in education and in hospitals. Think about it again."" He went on to defend Mr Blair's performance as leader, saying: "He fought and won three elections. Tell me another Labour leader who did that, another one who gave us minimum wage. Come on, grow up. The Labour leadership faced more criticism from the leader of another of the UK's big unions, who claimed Mr Miliband and senior colleagues were out of touch with working people. Paul Kenny, GMB general secretary, said Labour MPs were now "truly unrepresentative" of working people and dominated by career politicians, such as Mr Balls and Mr Miliband, who worked as advisers to Gordon Brown before becoming MPs.