The stimulus package, reduced from its original size of around $937bn, aims to cut taxes for the US middle class, boost construction projects and create up to four million new jobs.

Most Republicans, and some moderate Democrats, had opposed the stimulus plan, arguing it expanded government spending too much and did not include enough tax cuts needed to boost the economy.

No 'miracle cure'

Obama described on Thursday the stimulus package as essential to turn around the US economy, which has been buffetted by the subprime mortgage crisis, tight credit, failing banks and the global economic slowdown.

"Right now, we have a once in a generation chance to act boldly, to turn adversity into opportunity, and use this crisis as a chance to transform our economy for the 21st century," he said.

"That is the driving purpose of the recovery and reinvestment plan."

However, Lawrence Summers, director of the White House National Economic Council, told NBC on Friday that the stimulus package is not some "miracle cure" or "silver bullet" for the economy.

I think this is a key part of what's gong to be a multipart strategy to contain this decline," he said.

"[The problems] weren't made in a week, a month, a year. It's going to take time to fix."