The Tories have been accused of suppressing a report that calls for two new garden cities to combat the housing shortage.
Liberal Democrat party president Tim Farron suggested Conservatives were concerned that the proposals could alienate voters in their southern heartlands.
The report was initially commissioned nearly two years ago after Prime Minister David Cameron gave a speech supporting the idea of garden cities.
It is believed to float two potential sites in Buckinghamshire and Oxfordshire - where Cameron's own Witney constituency is.
Earlier this week Lib Dem deputy prime minister Nick Clegg signalled his continued support for new garden cities, saying he hoped plans would be published as soon as possible.
Farron told the Daily Telegraph: "It is time to break the log jam. This report needs to come out now and come out quickly. The Tories are displaying a Nimby attitude towards garden cities.
"We need to grasp this nettle and turn all these warm words about housing into action. For a growing number of people, the aspiration of home ownership, with all the security it brings, has become a distant dream. We need to do much more to help people realise their dreams.
"Garden cities offer a real chance for us to help tackle this problem and boost the economy."
Housing Minister Kris Hopkins said: "As promised in the coalition agreement, this Government has scrapped top-down Whitehall planning, included ending the last administration's failed so-called eco-towns programme which built nothing but resentment.
"Instead, this Government is committed to working with local communities to build more homes and promote sustainable development. This includes providing finance for those large scale housing projects that are locally-supported and have the full backing of the community."