The hiring of one of Barack Obama's top strategists will help Ed Miliband win against a Conservative campaign based on "fear and smear" at the next general election, Labour has said.
Douglas Alexander, the party's election chief, also admitted that the 2015 contest would be "tough".
But he praised new recruit David Axelrod's experience of fighting - against "negative" campaigns.
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Mr Axelrod's appointment has been viewed as a coup for the Labour team, which has seen its leads in the polls struggle in recent weeks. It trumps the high-profile hiring by the Conservatives last year of another former Obama aide Jim Messina. Mr Alexander hailed the hiring as "seriously bad news for the Conservatives".
Labour sources pointed to both Mr Axelrod's success rate in elections, but also to his track records in "backing winners".
Mr Axelrod and his firm will be paid a six-figure sum for advice in the run up to the 2015 vote.
The move should serve to reassure Labour MPs, at least in the short-term, following grumbling in recent weeks about their party's campaign tactics. Many were reassured last winter after Mr Miliband's announcement of an energy price freeze in his speech to Labour's annual party conference was hailed as a master stroke.
But jitters re-emerged after SSE's recent announcement of its own energy freeze, a year before Mr Miliband's policy would come into effect.
Poll ratings also suggested that the gap between Labour and the Tories had narrowed, doing little to ease fears.
Last night the Tories attempted to reawaken those fears pointing to claims that Mr Axelrod's firm advised an energy company as it campaigned to raise prices.
Mr Alexander said: "We believe that, given his track record, that he has a great deal to offer this campaign." He added: "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."
But he insisted the new signing would not lead to change of strategy. "(Mr Axelrod) 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 Axelrod is due to arrive in London next month for two days of strategy meetings with Mr Miliband and other senior shadow cabinet members. He will be supported by other former veterans of the Obama campaign.
Mr Axelrod said he'd had several conversations with Mr Miliband "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.
"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 ... I see the same thing happening in Britain."
Mr Axelrod's opposite number will be the Conservative adviser Lynton Crosby, an Australian.
The Liberal Democrats are also being advised by a South African strategy expert Ryan Coetzee.