By Emma Griffiths
Political reporter, BBC News, at the Labour conference
Lord Mandelson said Mr Brown 'grasps the big picture'
Business Secretary Lord Mandelson has said Labour must show it is "up for the fight" at the next general election.
At a fringe meeting at the Labour conference he said there was a "chasm" between their party and the Tories.
"That is something I welcome, it excites me, it doesn't daunt me," he told delegates.
He added it was unsurprising Labour were "the underdogs": "When the country takes a beating, the government takes a beating as well."
Lord Mandelson was one of a succession of ministers addressing the Progress meeting who urged Labour supporters to get geared up for the general election - which must be called by next June.
'Appetite for office'
He said there were some "organisational details and some fine tuning" to work through but during the conference week Labour had to show it was "up for that fight".
"We are up for it, so let's go for it," he said.
He accused the "Tory press" and "some in the BBC" of "writing off" the government but said people were not endorsing David Cameron's Conservative party.
"There's no policy area where the public think that during the last year or the last ten years we have taken the country in the wrong direction," he said.
The party was not "ideologically divided" as it had been in the 1980s, and ministers "don't look as though the have lost the appetite for office," he said.
An ICM poll for the News of the World found 11% of the 1,003 adults asked said Labour had a good chance of winning with Mr Brown and 48% said it had a slim chance. But 41% of those surveyed thought it probably or definitely has no chance.
But Lord Mandelson said: "I think a lot of people ... would rather have a man who know his own mind, grasps the big picture and all its complexities and sticks to his guns rather than a shallow flibberty gibbet who hasn't the guts to take on his own party."
"I can't remember a general election, and I have participated in many, where there was such a chasm between the two main parties and that is something I welcome, it excites me, it doesn't daunt me."
Health Secretary Andy Burnham also attacked Mr Cameron saying he had not taken on elements of his own party and that the Tories were still "the nasty party".
He said Conservatives like MEP Daniel Hannan - who suggested on American television that the NHS was a "60-year mistake" - felt they "can speak out now" was because they were emboldened and said Labour had to spell out what it stood for.
Chief Secretary to the Treasury Liam Byrne said there were beginning to be signs that economic policies pursued by the government were starting to have an effect.
He added: "In the next year we have to be confident and self confident that this election is there for the winning."