Ed Miliband: I can't beat Cameron on image
Labour leader Ed Miliband has attempted to confront his perceived image problem - by saying it is not his top priority.
In a speech launching his party's summer offensive, he said he was "not going to be able to compete" with David Cameron's slick approach.
But he said he wanted to offer voters "something different" at next year's general election.
"The leadership this country needs is one that has big ideas to change things," said the Labour leader.
Mr Miliband's personal ratings trail behind those of his party and in June fell to the lowest ever recorded in an ICM-Guardian poll - a distinction he shared with Deputy Prime Minister Nick Clegg.
Mr Cameron's ratings were also down but he remains well ahead of his two main rivals, particularly when voters are asked about who looks the "most prime ministerial".
Labour fears the Conservatives will target Mr Miliband personally at next year's general election, wrecking the party's chances of gaining power.
In what could be seen as an attempt to head off criticism, Mr Miliband spoke about some of the gaffes he has been accused of committing in recent months - including holding up a copy of The Sun and struggling to eat a bacon sandwich, as well as caricatures of him as Wallace from the Wallace and Gromit animations.
He said he wanted to stand up to powerful vested interests such as Rupert Murdoch, but added: "Sometimes you get it wrong. I know, especially for people on Merseyside, me holding up a copy of the Sun was one of those days."
Mr Miliband was forced to apologise last month after he was criticised by his own MPs for promoting the paper, which has been criticised for its reporting of the 1989 Hillsborough disaster, in which 96 people died.
The Labour leader said big ideas and principles were more important than image and Labour had the right policies on dealing with "the cost of living crisis", tackling low pay and building more homes.
By Brian Wheeler, political reporter
Ed Miliband is taking quite a gamble with this speech. He knows he has an image problem - and many in his party fear it could cost them the general election.
But a slick relaunch is out of the question - a cynical public would never buy it and, by his own admission, he couldn't pull it off.
So he has opted instead for a bit of of self-deprecation. Yes, I know I look a bit weird - get over it. That is his message.
But the danger is that by talking about his past PR disasters he is simply drawing more attention to them.
Also, whenever he stages a photo opportunity in the future - as all politicians do - he will be reminded of his words.
His political mentor Gordon Brown also tried to make a virtue of his own ineptitude in the field of public relations.
But "Gordon unspun" sounded to many people like yet more spin.
He said: "David Cameron is a very sophisticated and successful exponent of a politics based purely on image.
"I am not going to be able to compete with that and I don't intend to. I want to offer something different.
"I am not from central casting. You can find people who are more square-jawed, more chiselled. Look less like Wallace.
"You could probably even find people who look better eating a bacon sandwich.
"If you want the politician from central casting, it's just not me, it's the other guy."
But he said his version of political leadership was about sticking to principles even when it was hard, caring about people's lives and not leaving decency behind at the door of No 10, like the "callous Conservative" David Cameron.
Mr Miliband's speech, at the Royal Institute of British Architects in London, launched Labour's summer campaign, seen as an attempt to hit back at critics who accused the party of taking its eye off the ball during last year's parliamentary recess.
He said shadow cabinet members would be making a series of speeches about the "positive vision for the future from Labour".
Prime Minister David Cameron said Mr Miliband's speech proved that he was the leader who lacked substance.
"On a day when our national output has recovered to where it was before the great recession, which was brought to us by Labour, I think it was an extraordinary thing to say.
"The real substance is that because of the hard work of the British people we have actually reached a major milestone in our long-term economic plan."