John Prescott has apologised for letting Labour down over the past year.
The deputy prime minister has been at the centre of controversy over an affair with his diary secretary, and hospitality from a US tycoon.
As he brought Labour's conference to an end, he said: "I know in the last year I let myself down, I let you down. So conference, I just want to say sorry."
He confirmed he would stand down as Labour's deputy leader when Tony Blair leaves Downing Street.
Giving his last conference speech in the post, Mr Prescott thanked Labour members for their support in his 12 years as the party's number two.
"I'll never leave the political fight," he said, vowing to keep campaigning for Labour.
Three contenders - Jon Cruddas, Peter Hain and Harriet Harman - have already said they want his job and more looked poised to follow.
Mr Prescott's speech wrapped up the Labour conference, whose last day also saw Home Secretary John Reid signal that he may challenge Gordon Brown for the leadership.
After his speech delegates were shown a video of Mr Prescott's best moments, with the biggest cheer going to his punch on a rural protester during the 2001 election campaign.
Mr Blair and Mr Brown joined other ministers in singing the Red Flag and Jerusalem at the end of the session.
Mr Prescott said the last two leadership elections had been a credit to the party and said Labour must avoid the damage of disunity this time too.
"I've seen Labour governments, elected with big majorities, driven out within a few years as the party bitterly divided," he said.
Mr Prescott said he was proud of what he and Mr Blair had achieved together, despite occasionally agreeing to disagree.
"Tony, we all know the greatest tribute we can make to your time in office is to find within ourselves the energy, the vision, the commitment, and yes, the discipline to win a historic fourth general election victory," he said.
Mr Prescott hailed Labour's achievements in rebuilding cities, improving education and healthcare and leading the world when he negotiated the Kyoto deal on cutting greenhouse gases.
He said allowing the party to slip into opposition would be a betrayal of millions of people who he said rely on a government to make their lives better.
And he attacked Conservative leader David Cameron for hypocrisy and putting clever marketing above serious politics.
"If David Cameron thinks that a photo shoot of him hugging a husky dog and adopting an oak tree for their emblem could fool the British people into thinking that the Tories have fundamentally changed, he's barking up the wrong tree."