Cameron denies having jitters as the Saatchis come on board

News that Maurice and Charles Saatchi would be helping with the Tory election campaign was seen by some commentators as a sign that the party leadership was unhappy with advertisements which have been widely lampooned online.

It is thought that the Saatchi brothers – authors of hard-hitting campaigns like 1979's Labour isn't working poster, 1992's Labour's tax bombshell and the less successful Demon Eyes in 1997 – might bring a tougher edge to the campaign.

During a visit to Ellesmere Port in Cheshire, Mr Cameron was asked whether getting M&C Saatchi on board was a sign of pre-election panic at party HQ, as the Tory lead has slipped into single figures.

"No, not at all," he said. "We've got lots of people helping us in lots of different ways and you can be sure when the prime minister finally gets around to firing that starting gun we'll be fighting a very vigorous campaign."

A Tory spokesman said that the Saatchi brothers would be "part of the team" for this year's campaign alongside Euro RSCG, which was responsible for the high-profile poster featuring Mr Cameron's face earlier this year.

That poster was derided by Labour as "air-brushed" and led to a rash of online spoofs.

Lord Mandelson said the decision to turn to the Saatchis for help showed Mr Cameron was "too much PR and not enough PM" The Business Secretary added: "As if David Cameron needed more airbrushing."