Labour will campaign under the slogan "A Future Fair for All", it was announced as Gordon Brown prepared to put activists on a war footing.
In a significant escalation of pre-poll skirmishing, the Prime Minister will use a major rally today to launch what the party has dubbed "Operation Fightback".
Mr Brown will signal that the economy will dominate his appeal to voters - with efforts to secure recovery making up three of his four key themes.
In what aides described last night as an explicit "clarion call" to disillusioned Labour supporters, he will dismiss Tory claims to represent the "mainstream majority".
And ministers will be sent out across the country as part of what the party said would be a "street by street" fight for victory in the general election.
The weekend will also see Labour mailshots sent to thousands of voters in key marginal seats and local parties given "Operation Fightback" packs including magazines, stickers and "key doorstep messages" for campaigning "throughout the weekend and coming weeks".
But party sources played down suggestions the high-profile event signalled that Mr Brown had decided on an earlier election than the anticipated May 6 poll.
Unlike other parties, cash-strapped Labour is not holding a full spring conference so this weekend's 300-strong event is being used to effectively launch the campaign.
Political differences over how best to tackle the UK's record £178 billion deficit have dominated exchanges in the run up to the election.
Mr Brown yesterday renewed warnings that Tory plans to cut public spending this year risked plunging Britain back into recession - after 60 economists backed delaying action.
Setting out Labour's campaign priorities today, he will tell activists: "First, we must secure the recovery, not put it at risk.
"Second, we must support new industries and future jobs. Third, while we will reduce the deficit, we must protect and not cut frontline services.
"Fourth, we must stand up for the many not the few."
In a fresh bid to portray David Cameron's opposition as elitist, he will accuse the Tories of planning to "kick away the ladders of opportunity" and feigning "progressive" values.
"When you peel away the veneer and actually look at what their policies mean, what you see is it's not the new economics of the future, it's the same old Conservative economics of the past.
"They haven't moved on," he will say.
"At every stage the Tories want to kick away the ladders of opportunity, because they are not the party of Britain's mainstream majority and have policies that give most benefit for the few."
Labour's election co-ordinator Douglas Alexander said the party wanted to tap into a "submerged optimism" among voters about the future.
"If you look at the voters' mood there is anxiety and anger over bankers' bonuses, expenses and the recession, a general sense of grumpiness," the International Development Secretary told The Guardian.
"But sitting beneath that is a submerged optimism. What people want is a sense of a better future to come.
"We are not denying times are tough, but it has been a different kind of recession. Why is crime down, not up? Why is unemployment half what some people expected, including the Government?
"Why are repossessions lower than expected? Why if you look at the last recession under the Tories would you want to reopen old wounds and old divides?"
Mr Alexander said middle-income female voters with children were being targeted by Labour warnings that they would lose children's centres and tax credits if the Tories took power.
Shadow chancellor George Osborne said the PM should stop "dithering" and name the date for the election - which must be held by June 3.
"In the end the public have to decide in an election. I want that election as soon as possible.
"Instead of Gordon Brown having election rallies why doesn't he stop dithering and tell us when the election is actually going to be," he said.
A Conservative Party spokesman said: "Gordon Brown's election slogan tells you everything about where Labour themselves know they have failed: instead of creating a fair society over the last 13 years, Britain has become more unfair.
"Five more years of Gordon Brown won't change anything. Only real change with the Conservatives will put Britain back on its feet again."
Lib Dem leader Nick Clegg's chief of staff Danny Alexander said: "This slogan will only remind people of Labour's total failure to make Britain fairer.
"In Gordon Brown's Britain, social mobility is going backwards and a banker pays a lower rate of tax than their cleaner.
"That's not fairness. Gordon Brown is wrong if he thinks that slogans will make people forget Labour's failure."