Proceeds of the sale of 4G mobile phone licences should be used to "kick-start the economy", shadow chancellor Ed Balls has said.
Balls used his Labour party conference speech to reinforce his message that Labour could not pledge to reverse coalition spending cuts if it wins power in 2015 or "promise to put everything right straight away".
He put pressure on Chancellor George Osborne to ease his austerity programme by using the expected £3-£4 billion windfall from the sell-off next year of the superfast internet spectrum to boost the housing market and construction jobs.
Balls - who is under serious fire from trade unions over his backing of the coalition's public sector pay freeze, insisted that a Labour administration would tackle the deficit in a "fairer and more balanced way".
"The longer this government staggers on with a failing economic plan, the worse it will get and the harder the job will be," he warned.
"Hard times will last longer than all of us hoped, and we cannot promise to put everything right straight away.
"Because we all know there can be no post-election spending spree, in our first year in government we will hold a zero-based spending review that will look at every pound spent by government.
"Carefully looking at what the government can and cannot afford, rooting out waste and boosting productivity."
The lower estimate of the 4G revenue would be sufficient to fund a £500 million two-year stamp duty holiday on homes sold for up to £250,000 and the provision of shared ownership, affordable rent and social rent homes, he said.
At last year's conference he called for measures including cutting VAT to 5 per cent for home improvements, a one-year national insurance tax holiday for small firms taking on new staff and a banker tax to pay for jobs and homes.
But he said the need for a stimulus was now "even more urgent".
"With 119,000 construction jobs lost in two years and a 68 per cent fall in the number of affordable homes being built, we need bold and urgent action now," he said.
"In the good times, Labour used every penny of the £22 billion from the sale of the 3G licences to pay off national debt.
"But in difficult times, we urgently need to put something back into the economy.
"So with this one-off windfall from the sale of the 4G spectrum, let's cut through the dither and rhetoric and actually do something.
"Let's commit that money from the 4G sale and build over the next two years - 100,000 new homes - affordable homes to rent and to buy - creating hundreds of thousands of jobs and getting the construction industry moving again.
"Add to that a stamp duty holiday for first-time buyers, and we can deliver real help for people aspiring to get on the property ladder.
"A clear and costed plan to kick-start the economy and get people back to work. Building the homes that we need now and for the long-term.
"A vital step forward in renewing Britain's long-term infrastructure. Building our way out of recession and re-building Britain for the future."