Labour has branded Conservative leader David Cameron a "chameleon" in its first local election broadcast ahead of the 4 May poll.
Labour's attack on David Cameron
The film claims he changes his colour to suit his audience, "flip-flopping" between red, yellow and green.
Labour says he is "true blue" but learned from his brief career in PR to "change into any colour he pleased".
Mr Cameron joked he might put an image from it in his kitchen. He said his party's broadcast would be positive.
He argued the prime minister would be better advised to concentrate on tackling issues like the current problems in the NHS rather than being involved in such attacks.
"Labour are clearly showing that they have run out of steam run, run out of ideas, run out of positive things to contribute either at the local level or at the national level," he added.
Labour's film has been produced for the local elections but the party says it will use the theme even after polling day.
The broadcast accuses the new Tory leader of telling Labour supporters he is the "heir to Blair" and it mocks his green credentials.
"Dave the chameleon changed into every colour of the rainbow as he told everyone just what he thought they wanted to hear," it says.
"But underneath it all he was still true blue, through and through."
Labour plans to follow up the film with podcasts and mobile phone ring tones.
Asked why the party had decided to make a personal attack on Mr Cameron, Local Government Minister Phil Woolas said: "Well, it is funny.
"Of course there is a positive message. But it is also true that we are not prepared to allow David Cameron to get away with the strategy that he is pursuing, which is to say one thing to one audience and another thing to another."