The scheme was meant to help people hit by a sudden fall in income
Gordon Brown has been accused by the Tories of raising false hopes over a promised scheme to help people struggling with mortgage payments.
When the PM announced the Home Owner Support Scheme in December he said it would be available from early 2009.
The scheme will now be launched in April due to protracted negotiations with lenders over how it will work.
Ministers say it has not been delayed but the Tories say something has clearly gone "horribly wrong".
Shadow housing minister Grant Shapps said the scheme, which was meant to help people facing a sudden drop in income defer mortgage payments, was announced with such a "flourish" it had even "upstaged" the Queen's Speech on the same day.
But the details had not been fully worked out and lenders had not signed up to it to the extent Mr Brown had claimed, Mr Shapps alleged.
He told BBC Radio 4's The World at One: "It looks to me like an attempt to grab the headlines by the prime minister rather than actually deal with the problems."
He said it was "completely wrong for the government to announce a scheme where the details haven't been worked out and where months later people's expectations will have been dashed because actually they are still losing their homes rather than the scheme being in place."
Liberal Democrat leader Nick Clegg said: "The much-publicised Homeowner Mortgage Support Scheme announced last year has not yet helped a single family in trouble.
"The prime minister's wasteful complacency means that millions of extra families could be added to already full social housing lists."
Sue Anderson, of the The Council of Mortgage Lenders, said the apparent delay in implementing the policy had "caused consumers some confusion and some sense of not knowing where to turn in the meantime".
She said there had been a lot of discussion between the government and lenders about how the scheme would work and it had needed legislation to be passed before it could begin.
But she added: "When there is a gap between an announced policy measure and its implementation, inevitably people wonder what's happening and try to find out about that."
She advised people concerned about meeting their mortgage payments to "talk to their lender at an early stage".
Chris Tapp, director of debt relief charity Credit Action, said there had been slow progress on the scheme and the way it was announced had been "messy".
"The whole scheme has come together a little bit on the hoof," he said, and it was "confusing" for the public.
In December, Mr Brown said eight major mortgage lenders had signed up to the plan in principle.
But nearly three months later, the government is still locked in talks with lenders over how the scheme, which is meant to cover mortgages worth up to £400,000, will work.
The idea is that lender and homeowner will agree on the proportion of payment to be deferred up to 100% but the government is understood to have clashed with lenders over the extent to which it will underwrite it.
A spokesman for the Department for Local Government and Communities said the scheme had not been delayed as a firm date for its launch had not been announced until now.
Asked to explain the apparent delay, Chancellor Alistair Darling said people would be able to benefit from the scheme "fairly soon".
He told the Politics Show in Scotland: "Like many of these schemes, they've got to be worked up, the detail's got to be sorted out, but it will come into place very soon and I believe it will provide a lot of help to people, especially people who may unexpectedly find the family income's gone down and we want to help people stay in their house as long as possible."
Cabinet Office minister Liam Byrne said the government's "goal" was to get the scheme "up and running in April" but he stressed there five other ways in which the government was helping people struggling with mortgage payments.
These included the mortgage rescue scheme, in which housing associations take an equity stake in properties, and a deal with lenders not to repossess homes within the first three months of arrears.
He contrasted the government's approach with that of the Conservatives, who he claimed would "do nothing" to help people through the recession.
It comes as figures from Council of Mortgage Lenders (CML) suggest the number of homes in the UK repossessed by lenders rose last year by 54% to 40,000.
Despite the recession, the CML said this was fewer than it had originally predicted, but it expects repossessions this year will reach about 75,000.
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