Gordon Brown has urged voters to take a "second look" at Labour as he unveiled his election campaign themes.
Under the slogan "a future fair for all", he told a rally in Coventry that Labour would be "change makers" who stand up for "the many not the few".
And he attacked the Tories, saying they would put the economy "at risk".
Tory leader David Cameron said Labour had "badly damaged" the UK, while the Lib Dems said there had been a "total failure to make Britain fairer".
'Team of one'
Mr Brown opened his speech by stressing he had an "experienced" team behind him - paying tribute to senior cabinet ministers including Harriet Harman and Lord Mandelson - while the Conservatives were down to a "team of one".
Setting out his future aims, the prime minister said: "First, we must secure the recovery, not put it at risk. Second, we must support new industries and future jobs.
The event resembled a Jerry Springer-style chat show; with an invited audience of "real people" and a few audience "plants" - in this case cabinet members
"Third, while we will reduce the deficit, and reduce it by half, we must protect and not cut frontline services. And fourth, we must stand up for the many, not the few."
Appealing to former Labour voters who might have deserted the party, Mr Brown urged them to take a "long, hard look" at Conservative policies, which he said would put the recovery at risk and hurt ordinary families.
Families who wanted to "get on and not simply get by" should "take a second look at us and take a long, hard look at them," he said.
In an apparent reference to doubts within Labour about his own leadership - following an attempted coup by two former cabinet ministers in January - the prime minister admitted: "I know that Labour hasn't done everything right and I know, really I know, I'm not perfect.
"But I know where I come from and I know what I stand for and I know who I came into politics to represent."
In a separate interview broadcast on Channel 4 News, Mr Brown was asked to respond to reports that he was prone to outbursts of rage with his staff.
He said sometimes things were said "in the heat of the moment" but added: "If I get angry, I get angry with myself ... I have never, never hit anybody in my life."
There had been speculation that an election date might be announced at the speech but while Mr Brown told the audience there were 76 campaigning days left - he added he was referring to the local elections.
It is widely expected that the general election will also be called for 6 May - and all the main parties have been stepping up their campaigning efforts.
The Conservatives have already begun their poster campaign but Mr Brown said Labour's "secret weapon" would be its "beliefs" and the election would be won not on "who has the best PR" but on "values".
He also attacked Conservative leader David Cameron's call for voters to make 2010 "the year for change" after 13 years of a Labour government.
Mr Brown told supporters Labour were the "change makers" and the opposition were still committed to the "old Conservative economics of the past".
"How can they be the party of change when they haven't even changed themselves?" he said.
Labour has been involved in year-long talks with US President Barack Obama's team which have influenced Labour's campaigning tactics.
The party has been using its members to call thousands of voters in marginal seats.
Mr Brown told them the election would be fought "street by street, school gate by school gate, work place by work place and it's going to be won by you".
The full Labour manifesto will be launched later.
Britain 'more unfair'
The Conservatives attacked Labour's "fair future" slogan - releasing a list of 10 policies they said made Britain "unfair" - including Mr Brown's controversial decision to abolish the 10p tax rate and Labour's record on social mobility.
Shadow children's secretary Michael Gove: "After 13 years Labour, sadly, has failed"
Shadow chancellor George Osborne said Mr Brown's speech "had nothing positive or new to offer Britain".
In his regular webcast video posted on YouTube, Mr Cameron said Gordon Brown's claim to represent "the many" were "simply untrue".
Recorded before the prime minister's speech, he said: "The truth is it's the very people that Gordon Brown says he's fighting for who have actually suffered the most," he said.
"These were the people who put their faith in Labour to deliver a progressive future and a fairer society. But it just hasn't happened...
"It's the Conservatives that can say: We're not the party of the few... or even for the many... we're the party for everyone."
Speaking after the speech the Liberal Democrat leader Nick Clegg told the BBC: "Fairness is something real and what I think will make people feel very angry is to hear Gordon Brown talk about delivering fairness when he's failed to do so.
Nick Clegg: "Gordon Brown has failed to deliver on fairness"
"What does he have to say to the million youngsters who are without a job, what does he have to say to the pensioners who can't even heat their own homes... to say to the many families in this country who are struggling simply to pay to put a warm meal on their table every day?
"He has failed to deliver fairness, he doesn't deserve a future as the prime minister of this country."
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