Gordon Brown has staked his claim to be the only man to steer Britain through tough economic times saying: "This is no time for a novice."
In a speech to Labour's conference, he said the Tories could not be trusted to run the economy and vowed Labour would not stop fighting for a "fair society".
He also pledged to scrap prescription charges for people in England with cancer from next year.
And in a surprise move, Mr Brown was introduced to delegates by wife Sarah.
In a more personal conference address than normal, Mr Brown said he had been "stung" by criticism of his decision to scrap the 10p tax rate and vowed he would never again be accused of not being on the side of "hard working families".
He also took a swipe at politicians who use their families to gain media coverage, saying: "My children aren't props - they're people."
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The comment was seen as an attack on Tory leader David Cameron - but it was also seen by some pundits as a coded warning to would-be supporters of David Miliband, who has been at the centre of leadership bid speculation.
This was denied by ministers Jacqui Smith and Geoff Hoon who both blamed the media for stirring up leadership talk and hailed Mr Brown's speech.
Schools Secretary Ed Balls, a close ally of the prime minister, said he believed Mr Brown's critics within the party were already having "second thoughts" after a "very united" conference.
"I think people's gut instinct after hearing that speech will be that Gordon Brown is the right man for these times and that we can win the next election," he said.
Foreign Secretary David Miliband - who has dismissed as hearsay a BBC report that he was overheard saying he went as far as he could in his own speech without it being seen as a "Heseltine moment" - said Mr Brown's was an "excellent speech".
And Labour backbencher Ian Gibson, who said earlier this week that Mr Brown needed "an Obama moment" said: "It was absolutely brilliant. He delivered it humbly but with a passion we don't often see in Labour politicians."
Dave Prentis, general secretary of Unison, said Mr Brown had "put clear red water between Labour and the Conservatives" and had put the Tories "back in their box".
But shadow chancellor George Osborne -who was singled out for criticism in the speech - said Mr Brown had retreated to the left "to save his job".
"There was nothing really new in the speech - no apology for the mess he's got the country into and no new ideas that show us how he's going to get us out of it," he said.
"A divided government and a weak prime minister are the last things that the country needs at a time of crisis."
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