David Cameron says 95% government-backed mortgages to help people get on to the property ladder will start within days.
The scheme was due to start in January but hours before the Conservative Party Conference opened, the Prime Minister revealed that NatWest, RBS and Halifax had all agreed to provide the new deals.
It is widely being seen as a response to Ed Miliband's Labour conference crowd-pleasing announcement that the party would freeze energy prices for two years as conference season has shaped up as a "battle over the consumer".
Speaking on Sunday morning, Mr Cameron said that it was ridiculous that people could afford mortgage repayments, but not the deposit to get the loan in the first place.
The Prime Minister said that only those with well-off parents could manage to get on the housing ladder, telling BBC One's Andrew Marr Show: "I'm not going to stand by while people's aspirations are trashed."
He denied that the move would create a housing bubble and said that they had taken advice from the Bank of England and empowered it to stop a bubble being created.
As the Conservative Party Conference began, 50,000 people took to the streets to protest over changes to the health service in a Save Our NHS campaign march. Police said the protest was one mile long.
The mortgage guarantees planned by the Government will allow buyers to acquire a newly built home or an existing property worth up to £600,000 with a deposit of only 5%.
The second stage of the Help to Buy scheme aims to boost mortgage availability by reducing the risk for lenders because the Government takes on the risk of default when it guarantees a proportion of a loan.
In a wide-ranging interview ahead of the conference Mr Cameron also said:
:: He was sorry he did not win the 2010 election and made it clear he was looking for a straight Conservative victory in 2015.
:: The high-speed rail HS2 project would stay on its £42.6bn budget
:: That Britain could pull out of the European Convention on Human Rights, which has prevented the UK deporting foreign criminals
:: He would never back a mansion tax, marking a clear coalition red line
:: Televised leaders debates should take place before campaigning for the 2015 election begins.
Mr Cameron also spoke about Mr Miliband's energy bill freeze proposals saying: "I want to lower prices not just for 20 months but for 20 years."
He said that he wanted to look at "all those markets" and make sure they were "working for hard-working people".
Sky News Political Correspondent Anushka Asthana said bringing forward the mortgage plan and the announcement, on Saturday, of tax breaks for married couples was an attempt to give Conservatives something to "take to the doorsteps".
She said: "This is also about Mr Cameron looking outwards and thinking about the public and trying to come back on some of the ideas that Labour and the Liberal Democrats have put forward over the past few weeks.
"People are calling this the battle over the consumer. At the Lib Dems we have free school meals and then Ed Miliband promises to freeze energy prices. The Tories have tried to rubbish that idea but at the same time they are clearly worried."
The Chancellor, George Osborne, tweeted the news that RBS, NatWest and Halifax had all signed up to the mortgage scheme.
A YouGov poll for The Sunday Times put Labour on an 11 point lead on 42%, with the Conservatives at 31%, UKIP on 13% and the Liberal Democrats trailing on 9%.
The 95% mortgage scheme has previously attracted widespread concern, with some claiming it may lead to more problems than it solves.
Liberal Democrat Business Secretary Vince Cable warned the scheme "could inflate the market" and said he feared there was a "danger of getting into another housing bubble".
Former Bank of England governor Lord King said the scheme is "too close for comfort" to a general scheme to guarantee mortgages.
Speaking on Sunday, Labour's shadow chancellor Ed Balls said: "If David Cameron is serious about helping first-time buyers he should be bringing forward investment to build more affordable homes. Rising demand for housing must be matched with rising supply, but under this government house-building is at its lowest level since the 1920s."
The first stage of Help to Buy was launched in April and offers loans to give people the chance to buy a new-build home with a deposit of just 5%. The scheme has been credited with spurring a surge in home sales and driving up prices.
:: Watch Conservative Party conference coverage live on Sky News