Labour hopes the recruitment of o ne of US President Barack Obama's top strategists will prepare Ed Miliband's party for a "tough" 2015 general election campaign.
Douglas Alexander, Labour's election supremo, said David Axelrod had experience of "fighting negative campaigns" and was prepared to combat "fear and smear" attacks from the Tories.
Securing the services of Mr Axelrod, who will be paid a six-figure sum for his advice, has been hailed by Labour as a major coup - and "seriously bad news for the Conservatives" - at a time when Mr Miliband has been under fire from sections of his own party for his campaign tactics.
Mr Alexander said: " We are expecting significant support from David Axelrod over the coming months. He is coming to the UK next month for discussions with Ed Miliband and senior members of the shadow cabinet.
"We believe that, given his track record, that he has a great deal to offer this campaign. He has been able to get middle class Americans to support a progressive political project, he is used to winning big majorities and he is used to discrediting negative personalised attacks."
He added: "He is well used to fighting negative campaigns and I'm afraid we expect a campaign of fear and smear from the Conservatives."
Mr Alexander told BBC Radio 4's Today programme that the 2015 contest was a "quintessentially winnable election".
He said: "We anticipate this is going to be a tight election and a tough campaign, I can't think of anybody I would rather have alongside me in the trench than David Axelrod."
The announcement was said to mark the end of several months of negotiations by Mr Alexander, the shadow foreign secretary and the chair of Labour's general election strategy, to secure the services of Mr Axelrod and those of his firm AKPD.
The party said he would become an integral part of Labour's team, working closely with Mr Alexander, campaign director Spencer Livermore, and the party's senior pollster Stan Greenberg. He will also take part in regular strategic discussions with Mr Miliband and the Labour campaign team.
Mr Alexander indicated that the Labour leader and Mr Axelrod agreed on the biggest "generational challenge" facing politics - how to address the breakdown in the link between economic growth and family finances.
Labour's focus on cost of living issues has come under scrutiny as the latest figures showed wages had risen faster than inflation, but Mr Alexander insisted it was still a major concern - and one shared by Mr Axelrod.
"He understands, as we do, the defining challenge of not just the economy but, we would argue of this generation of political leaders. In that sense some people have suggested that the argument about cost of living is somehow running out of steam, we actually believe this is a Government that is running out of time and that the ongoing cost of living crisis is both deeper and broader than many people have realised."
Mr Alexander promised an election manifesto that would be both radical and credible.
"Given the challenges that we are facing as a country, we have to offer a manifesto printed in bold colours not just pastel shades. We have set out radical policies already, but we recognise as a generation that the real trade-off is not between being radical at the cost of being credible, or credible instead of being radical," he said.
"What we recognise is that people will simply dismiss you if you are offering more of the same, but equally if they don't trust you with the public finances then they are not going to vote for you."
Mr Axelrod is due to arrive in London next month for two days of strategy meetings with Mr Miliband, deputy leader Harriet Harman, and other senior shadow cabinet members.
He will be supported by other veterans from the Obama for America campaign, including Larry Grisolano and Mike Donilon, as AKPD picks up the pace of its work with Labour from the early months of next year.
Mr Axelrod said: "I've had several conversations with Ed Miliband over the course of the last year in which I have been struck by the power of his ideas, the strength of his vision and the focus he brings to solving the fundamental challenge facing Britain.
"He understands that a growing economy demands that you have to have broad prosperity. We can't just have prosperity hoarded by a few where people at the top are getting wealthier and wealthier but people in the middle are getting squeezed.
"This is a problem not just for Britain but everywhere in advanced economies, including here in the US. Ed Miliband has a real vision of where we need to go to solve those problems. He has answers to these questions which will be very potent in the next election.
"That is how we won in the US. Barack Obama articulated a vision which had, at its core, the experience of everyday people. And everyday people responded, they organised and they overcame the odds. I see the same thing happening in Britain."
Labour's Baroness Prosser, a former party treasurer, criticised the decision to spend so much money on Mr Axelrod.
She told BBC Radio 4's PM programme: "I'm not that enthusiastic, to be perfectly honest. I do hope that this appointment will make a difference and that Labour will romp home. That's the name of the game.
"Having said that, I can't really see how a decision has been made to spend that six-figure sum on one person when what we really need is lots and lots of organisation going on around and about in the country to turn out the vote.
"Because no matter how brilliant the message, no matter how organised everything is at the top level, if we don't get people coming out of their houses and voting on polling day then we are not going to win and, in order to get people out, we have got to have a message at local level that really means something, a message which they understand, which is clear and which they know will make life better for them."