Harriet Harman has defended using a pink bus promote a campaign drive targeting the nine million women who failed to vote in the last general election.
Labour's deputy leader will spearhead the "woman-to-woman" campaign which aims to visit more than 70 constituencies in the run-up to the main election campaign.
Harman said the decision by the party to mount its first "proper" women's campaign - with a pink, 16-seater minibus touring the country - reflected the need to demonstrate that politics was not just a "men-only" activity.
"We don't want women to give up on politics. If you look at the figures, the disaffection that there is with politics is even more pronounced among women," she said, pointing to the 9.1 million women who failed to vote in the 2010 election.
"We want women to feel that this is their democracy and politics is for them as well as for men. Politics is too important to be left to be a men-only activity. We are saying this is a woman-to-woman activity."
Harman said that while Labour would be highlighting policies on issues such as childcare and domestic violence, David Cameron and the Conservatives had nothing to offer female voters.
At a briefing for Westminster journalists, she poured scorn on the Tories for having auctioned a shoe-shopping trip with Home Secretary Theresa May at the party's fundraising Black and White Ball.
"Whilst the Tories are auctioning a shoe-shopping trip with Theresa May, Labour is out there having a real discussion with women in all parts of the country," she said.
While she rejected suggestions that the campaign was "patronising" to women, she was reluctant to be drawn on the choice of a pink bus, saying that the colour had been picked by "a collective".
"Is it not magenta or something?" she joked. "We wanted to mark that this was something different. We wanted it to look conspicuous and therefore a white van was not going to do the job."
She added: "It is a very nice looking bus.... It is the correct colour. This is a One Nation Labour colour."
Tory MP Caroline Dineage said: "The wheels have come off the Labour bus. Getting Harriet Harman to drive around the country in a pink van to try and attract the female vote is as patronising as it gets. This is clearly just another divisive gimmick that the electorate will see through".