The Conservatives have been accused of suppressing a report which recommends building two new garden cities to combat the housing shortage.
Liberal Democrat president Tim Farron said his coalition partners feared alienating voters in southern England ahead of the general election.
Mr Farron said he believed the report identified two potential sites - in Buckinghamshire and Oxfordshire.
The Conservatives denied any delay and said plans would be outlined for 2015.
The report was initially commissioned following a speech by Prime Minister David Cameron two years ago in which he supported the idea of new garden cities to help alleviate the housing situation.
Mr Farron has now accused the Conservatives of deliberately suppressing its publication.
The sites would provide thousands of homes and include schools, transport and infrastructure to support whole new communities.
Mr Farron said there was clearly a housing crisis - and the garden cities could provide a solution - but the Conservatives feared provoking an angry response from voters in Tory heartlands.
He told the Daily Telegraph the "log jam" needed to be broken.
"This report needs to come out now and come out quickly. The Tories are displaying a Nimby attitude towards garden cities."
Earlier this week, Lib Dem leader Nick Clegg expressed his continued support for the idea in the Commons, and said he hoped plans would be published as soon as possible.
Government plans for new garden cities have run into opposition from local authorities.
Communities Secretary Eric Pickles has reportedly said he would not "impose" the developments on areas that did not want them.
Housing minister Kris Hopkins said: "As promised in the coalition agreement, this government has scrapped top-down Whitehall planning, including 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."
Shadow chancellor Ed Balls has said Labour would launch the biggest programme of new town construction in decades.
His party is committed to building 200,000 new homes a year by 2020.
Twenty-seven new towns sprung up across the UK after World War Two, including Stevenage, Harlow, Milton Keynes, Corby, Cwmbran, Newton Aycliffe, Peterlee and Cumbernauld.