The outdoor drive by Euro RSCG features pictures of ordinary people and the strapline 'I've never voted Tory before, but we've got to fix our broken society'.
It will appear on more than 1,500 sites in England, Scotland and Wales and was unveiled today by Tory leader David Cameron and party chairman Eric Pickles.
The posters urge viewers to visit the which links to YouTube films, created in-house, of the people featured in the ads explaining why they are switching their allegiance.
A previous campaign with a prominent picture of Cameron was widely spoofed by Labour bloggers and a spoof of this latest ad has already been posted on the Labour Party's website.
.jpg)
.jpg)