Gordon Brown starts his political fightback today with measures to help first-time buyers and homeowners facing repossession.

The Prime Minister is expected to stand alongside Alistair Darling, the Chancellor, as he announces proposals aimed at injecting well over £500 million into the stalling housing market and protecting the most vulnerable. But simmering tensions at the heart of his administration and widespread disillusionment among voters mean the housing package and a similar set of measures on fuel have only a limited chance of success.

Downing Street sought to dampen speculation that Mr Darling’s warning that Britain faced the toughest economic challenge for 60 years had caused a rift with Mr Brown. Whitehall insiders suggested that Mr Darling had put his job on the line and said that he was wrong to say there would be no autumn reshuffle.

Although Downing Street insisted that Mr Brown had full confidence in Mr Darling, the confusion over the form of today’s announcement added to the disarray. Downing Street indicated at lunchtime that Mr Darling would not attend the announcement of the housing package, but senior government sources said later that he would, along with Hazel Blears, the Community Secretary.

The first stage of Mr Brown’s relaunch centres on a mortgage rescue scheme, which will hand councils and housing associations the power to help vulnerable families facing repossession. Struggling homeowners will be given the option of selling their homes outright and renting them back, selling a portion of their property or applying for a special loan to help to reduce their mortgage payments.

Mr Brown will give first-time buyers help in the form of a new product, HomeBuy Direct. Those earning less than £60,000 a year will be eligible to apply for a loan of up to 30 per cent of the value of a new-build house. The loans will be backed by the Government and the housing developer, and will be free for five years. Mr Brown is hoping that this will also help home-builders and construction companies, many of which are sitting on thousands of empty flats and houses built during the property boom.

The Government will also bring forward funds to speed up the development of social housing. It is not clear how much the total housing package will be worth but sources indicate it will be below £1 billion.

Mr Darling has refused to approve a suspension of stamp duty for the cheapest houses, amid continuing tensions with No 10 over the extent of the package.

The scale of the challenge facing Mr Brown is shown in a new Populus poll for The Times, undertaken last weekend. Voters welcomed most of the expected proposals, but only a small minority think that they would make a significant difference to their economic situation. As many as 83 per cent say that the Government should spend more to help to make buying a house more affordable and to get the housing market moving again. But only 33 per cent believe that this would make a significant difference, and 64 per cent little or none. While 58 per cent support a one-off windfall tax on energy companies, only 22 per cent think that it would make a significant difference and 73 per cent little or no difference.

There is a similarly stark contrast with a suspension of stamp duty on all house purchases. This is backed by 70 per cent of voters, but only 30 per cent think it would make a big difference, and 67 per cent little or none.

The poll shows no change in voting intentions for the main parties compared with late July, with the Conservatives on 43 per cent, Labour on 27 per cent, the Lib Dems on 18 per cent, and other parties on 12 per cent. This confirms the pattern since the spring with Labour well below 30 per cent and the Tories in the mid-forties.

David Cameron and George Osborne maintain their lead over Mr Brown and Mr Darling on who is most trusted to deal with Britain’s economic problems in the months and years ahead, by a margin of 39 per cent to 30 per cent. This contrasts with the 61 per cent to 27 per cent balance in favour of the Labour team a year ago. .

The dismal state of the housing market was highlighted by new figures that showed the number of loans approved for homebuyers slumped to a record low in July. Lenders approved only 33,000 mortgages for house purchases in July, figures from the Bank of England show. This a 71 per cent drop from July last year and the lowest figure since the series began in 1993. New buyers are being put off by demands for hefty deposits from lenders as well as falling house prices.

The lack of buyers is helping to drag down house prices further as sellers are forced to cut asking prices to secure a sale. House prices have fallen by more than 10 per cent in the past 12 months, according to recent figures from Nationwide Building Society.

Howard Archer, of Global Insight, the economic consultancy, said that the figures were very disturbing. “They heighten concerns over the potential depth and length of the housing market correction,” he said.

Lenders are likely to welcome new measures to allow councils to help struggling homeowners but there were calls for more wide-ranging schemes to kick-start the market. Sue Anderson, of the CML, said: “Measures designed to help the casualties of the current conditions are welcome, but are unlikely to bring health back to the market more generally. We have to be cautious.”

Populus interviewed a random sample of 1,506 adults aged over 18 by telephone between August 29 and 31. Interviews were conducted across the country and the results have been weighted to be representative of all adults. for more details, see www.populus.co.uk.

Who could replace Alistair Darling?

David Miliband

(9-4) Moving the Foreign Secretary to the front line of the credit crunch would bind his future more closely to Gordon Brown’s. But – if he agreed to take the job – would an ambitious Chancellor with his own designs on No 10 be able to work effectively and in harmony with the Prime Minister?

Ed Balls

(40-17) Brown’s allies have been whispering for months that the Schools Secretary would do a better job at the Treasury. But such an appointment would be symbolically damaging, suggesting that the Prime Minister had retreated into the bunker and trusts no one beyond a tiny cabal around him

John Hutton

(12-1) Might restore confidence in the City weakened by the nondoms and capital gains tax fiascos after performing well in the eyes of business. But a controversial figure in the party, leading opposition to a windfall tax. And, as a leading Blairite, does Brown trust him enough for a bigger job than Business Secretary?

Ed Miliband

(13-1) One of the few untarnished Cabinet members who is also close to Mr Brown. When his brother, David, wrote the now famous Guardian article at the start of the summer that failed to mention Mr Brown, Ed stayed in the background and said nothing, earning Brownie points. But could too many Milibands at the top table be problematic?

Alan Johnson

(16-1) When Mr Miliband seemed to be gearing up for a leadership challenge, many on the Centre and Left asked whether the Health Secretary might be persuaded to run too. If No 10 does fear Mr Johnson, putting him in the second-most-difficult job in government might be a way of testing his ambitions

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