President-elect Barack Obama has proposed tax cuts and a rapid dash to a green economy in his first major policy speech since his election.
Mr Obama said that massive stimulus spending was essential to avert a long and grinding recession.
'I don't believe it's too late to change course, but it will be if we don't take dramatic action as soon as possible,' Mr Obama said.
'If nothing is done, this recession could linger for years,' he said, in an appeal both to Congress and to the public to back a stimulus bill that is expected to total at least $775bn.
Republicans are baulking at the costs and query how much of the money will actually stimulate growth to haul the world's largest economy out of its year-old contraction.
But Mr Obama said the economic costs of not launching a huge stimulus would be far worse, even in the face of a budget deficit that is forecast to top one trillion dollars this year.
Without action, Mr Obama warned 'the unemployment rate could reach double digits,' an entire generation's potential might be thwarted, and the US could lose its global competitive edge.
'In short, a bad situation could become dramatically worse,' he told an audience at George Mason University in Virginia.
Mr Obama has already vowed a nationwide program of repairs to 'crumbling' roads, bridges and schools, a rollout of broadband Internet across rural America, and federal aid to cash-strapped US states.
In the speech, he pledged a 1,000 dollar tax cut for 95% of working families as the 'first stage' of a program of tax relief that would extend into the government's next budget.
Production of alternative energy would be doubled in the next three years, Mr Obama said, and more than 75% of federal buildings and 2m homes would be modernised to cut billions from power bills.
The president-elect promised a new 'smart' electricity grid to cut blackouts and deliver the new modes of energy to homes and businesses.
And he said all patients' medical records would be computerised within five years, saving billions and saving lives.
'I understand that some might be skeptical of this plan,' Mr Obama said.
