Harriet Harman said Labour had proved its unity in the face of criticism
Gordon Brown has proved his "critics wrong" and has begun Labour's "fight back", Harriet Harman has said.
In her closing speech to the party conference, Labour's deputy leader said members had shown unity where people had expected "division and disunity".
But, amid rumblings about Gordon Brown's leadership, she said supporters expected MPs to remain "loyal".
She accused the Conservatives of "breathtaking arrogance", saying leader David Cameron was "not quite right".
After a week in which Gordon Brown's leadership has been under intense scrutiny, Ms Harman said the prime minister had confounded his doubters.
"He has shown that he is the right person to lead the party and the right person to lead this country," she said.
Mr Brown's "strength and resilience" would be vital in guiding the country through difficult economic times, she added.
Ms Harman said Labour would take "no advice" from the Conservatives on key issues affecting the country, accusing the party of having no solutions to the current financial crisis.
In a personal attack on Mr Cameron, she said there was something not "quite right" about him.
"He's the kind of man your mother used to warn you about," she said. "He'll promise you the world. But if he ever got his wicked way with you - in the ballot box - you'd never hear from him again."
Laying out Labour's challenge in the run-up to next year's local and European elections, Ms Harman said its "fight back" had begun.
The final day of Labour's conference has been overshadowed by the news that Transport Secretary Ruth Kelly is to leave the cabinet at a reshuffle expected next week.
The mother-of-four said she wanted to spend more time with her young family although some commentators have said she was unhappy about the government's direction.