The credibility of the coalition's £310bn plan to boost Britain's infrastructure and help the economic recovery has been questioned by MPs.
The Public Accounts Committee (PAC) urged ministers to be "realistic" about how much private and public investment can be raised as the economy stalls.
And it warned that consumers would be left shouldering the main burden of the costs through higher rail fares and utility bills.
The National Infrastructure Plan first launched in 2010 and was updated last December.
It lists projects worth £310bn - £200bn of which are to be wholly funded by the private sector.
The committee stressed that investment in power generation facilities, roads, railways, airports, ports and communication systems was "crucial for stimulating economic growth".
But it said: "We are not convinced that a plan requiring £310bn of investment in infrastructure is credible given the current economic climate, the cutbacks in public finances and the difficulty in raising private finance for projects on acceptable terms."
The Treasury says it has prioritised 40 programmes but the committee claimed many of these are broad and that there are 200 individual projects "whose relative priority is not clear".
"The Treasury should assess how much investment can realistically be financed and develop a coherent strategy using tightly defined criteria to identify and prioritise project," it said.
The report also cautioned that investors would be reluctant to come forward with money "until government policy is clear and consistent".
Margaret Hodge: 'This is not a real plan'
PAC chair Margaret Hodge described the plan as "a long list of projects requiring huge amounts of money, not a real plan with a strategic vision and clear priorities".
She said: "Most of the £310bn of investment needed will come from the private sector, with households shouldering the cost through higher energy bills and fares.
"Family budgets are already badly squeezed and inevitably those on the lowest incomes will be hit hardest. The Government needs to urgently assess the impact on consumers and how this can be contained."
Mrs Hodge also warned that taxpayers' money might have to be used to attract investors and that the lack of money could increase Britain's vulnerability over energy supplies.
"It is likely that the UK will have to buy ever more energy from overseas and at a higher price due to the failure to secure investment," she said.
The Treasury said it did not agree with the committee's depiction of its plans and insisted long-term infrastructure was a central priority.
"Government regularly monitors progress and at the Budget published details of delivery of the top 40 infrastructure projects," a spokesman said.
"As well as switching billions of pounds from current to capital spending, we are also using the Government's balance sheet to provide vital funding.
"Last week, Drax Power became the first recipient of a UK Guarantee, with the Treasury underwriting £75m of investment in biomass energy."
Which? executive director Richard Lloyd agreed investment was vital but insisted it could not be at any cost to already-struggling consumers.
"In economic times like these it's all the more vital that ministers take into account the full impact on hard-pressed households, and avoid imposing any unnecessary extra financial pressure on those that foot the bill for Government-backed projects, as consumer spending will be central to economic recovery," he said.