US President George W Bush is calling for members of Congress to agree quickly on the terms of an economic stimulus package that would be worth about $145bn (£74bn) and help offset the effects of declining house prices, higher energy costs and sluggish job creation.
Mr Bush said tax cuts should top attempts to revive the US economy
Mr Bush was speaking at the White House as concern grows in the US about falling economic growth.
He said the country's economy remained vibrant and resilient, but that it was occasionally necessary for government to provide a "shot in the arm" in uncertain times.
"Our economy has a solid foundation," he said, "but there are areas of real concern."
He called for Congress to put together a "growth package" that would be worth about 1% of the US gross domestic product (GDP).
That is on the high side of what economists and political leaders had been recommending in recent weeks.
Mr Bush said tax cuts should dominate the government's attempts to shore up the sagging economy.
With US tax deadlines only months away, Bush administration officials are talking about sending rebate cheques of up to $800 (£409) for individuals and $1600 (£819) for households.
"Letting Americans keep more of their own money should increase consumer spending," the president said, adding that consumers would be free to pay off crippling domestic bills and fund higher prices at the petrol pump.
Mr Bush said his treasury secretary, former investment banker Henry Paulson, was leading the administration's efforts to reach agreement with Congress.
"While I am confident in our long-term economic strength, the short-term risks are clearly to the downside, and the potential cost of not acting has become too high," Mr Paulson told journalists after the president's speech.
On Thursday, the chairman of the US Federal Reserve, Ben Bernanke, testified to Congress that a timely, targeted economic stimulus package would shore up his own efforts to avert a further slowdown.
"Putting money into the hands of households and firms that would spend it in the near term" should be the priority, he said.
Economic growth has been slowing drastically for months in the US, with a once-booming housing market in the doldrums and inflation edging upwards along with record oil prices.
Mr Bernanke said the economy was not in recession, an assessment that puts him at odds with leading investment banks that have already begun using what's known here as "the R-word" to describe the US economic outlook for 2008.
So far, financial markets seem sceptical that any stimulus package broadly acceptable to Mr Bush and Congressional leaders can have sufficient impact on the $14 trillion US economy.
Presidential hopefuls have been unveiling their economic plans
The FTSE 500 in Britain has lost almost 5% of its value in the past week, with Wall Street and other stock exchanges showing similar volatility.
With the US presidential primaries in full swing, political pressures to put together an economic stimulus package are acute.
The differing views of Democratic and Republican candidates and Congressional leaders are well known - the Democrats favour direct government spending to help people most at risk while the Republicans want tax cuts that help businesses and families alike.
Analysts say both parties' candidates will be acutely aware of the scrutiny of middle-class voters as they cross the country, campaigning in many areas already hard hit by higher inflation and the sagging housing market.