Nick Clegg has indicated he could back "radical" action to increase the number of women in his parliamentary party as he claimed Labour and the Tories were able to dish winnable seats out like "consolation prizes" to would-be MPs.
The Deputy Prime Minister acknowledged that the Liberal Democrats in Westminster were "too male and pale" and did not properly reflect modern Britain.
He has already indicated that he would back all-female shortlists for seats if action to encourage more women into parliament did not work, but accepted there would have to be a debate about the issue within his party.
On BBC Radio 4's Woman's Hour he said: "Our parliamentary party is too male and pale. If we want to represent modern Britain we have to have modern Britain represented in us."
He added: "O ne of the challenges we have as a party - unlike the two larger parties - is that they can disperse constituencies and candidacies for winnable seats a bit like consolation prizes around to candidates.
"We can't do that because we always have to painstakingly work year in, year out before people even win elections."
Mr Clegg said the party was offering financial support and mentoring to women, disabled or ethnic minority candidates, giving them "particular help to make sure they cross the line".
He said: " I hope that works but if it doesn't I actually, personally - I stress there will be debate about this - personally, I have come to the view, if a little reluctantly, that something more dramatic, maybe on a temporary basis, reserving certain constituencies for women, might be the kind of thing we need to do.
"The Liberal Democrats, for perfectly impeccable liberal reasons, have always been reluctant to do that - the worry is it smacks of tokenism and so on - but I accept that we now need to deal with this.
"If we don't deal with it through the way we are trying to then we will need to deal with it in a more radical fashion."
Mr Clegg, who has championed changes to parental leave and childcare in government, insisted he was not discriminating against stay-at-home mothers.
"I don't believe it's for the state or the government or the politicians to cast personal judgments on the choices that people make in their lives," he said.
The Lib Dem leader said he had "lots of friends who are mums" who stay at home.
"It's not for me to judge, it's for me to celebrate that choice if that's what they think is right for them and their family," he said.
He dismissed as a "bung" the Tory-led policy of a tax break for married couples, claiming it discriminated against couples who had not tied the knot.